Iga Swiatek dragged Poland into the semi-finals of the United Cup with inspired performances in her singles and doubles matches against Italy.

Poland trailed after Lorenzo Musetti and Matteo Berrettini secured wins against Daniel Michalski and Hubert Hurkacz respectively, only for Swiatek and Magda Linette to level things with respective singles victories over Martina Trevisan and Lucia Bronzetti.

That sent the Brisbane city final to a decider in the mixed doubles, which Swiatek and Hurkacz won with ease 6-1 6-2 against Musetti and Camilla Rosatello, though there was a pause in the second set to dry rainfall on the court.

Despite defeat, Italy also advanced to the final four as the city finals loser with the best record.

It was more routine in Sydney as the United States eased to a 4-1 win against Great Britain.

Madison Keys came from a set down to beat Katie Swan, while Jessica Pegula eased past Harriet Dart 6-2 6-0 after Cameron Norrie had defeated Taylor Fritz in three sets.

Despite going a set behind, Frances Tiafoe came back to beat Dan Evans 3-6 7-5 6-3 to clinch the win for his country, before Pegula and Fritz added some gloss after beating Dart and Evans in the mixed doubles.

The third city final in Perth included a thriller as Greece's Stefanos Tsitsipas beat Borna Coric 6-0 6-7 (4-7) 7-5. Donna Vekic had no trouble getting Croatia on the board as she eased past Despina Papamichail 6-2 6-0.

Maria Sakkari put Greece 2-1 ahead when she beat Petra Martic 6-3 6-3, but Borna Gojo defeated Stefanos Sakellaridis in straight sets to make it 2-2.

However, Greece secured the win and their place in the last four after the pairing of Sakkari and Tsitsipas saw off Martic and Gojo 7-6 (8-6) 6-4.

Greece will take on Italy in the semi-finals, while Poland face the USA, with both taking place in Sydney on Friday.

Daniil Medvedev cruised into the quarter-finals of the Adelaide International with a straight-sets victory over Miomir Kecmanovic on Wednesday.

The Russian, seeded third in South Australia, made short work of his Serbian opponent in a 6-0 6-3 win to reach the last eight with little hassle.

"It's always better to win 6-0 than to win 7-6 saving nine set points and playing one hour, 20 [minutes]," Medvedev said.

"But tennis is not as easy, otherwise everyone would be number one, but we have only one. So happy with my level today against a strong opponent. Second set was tougher, but managed to close it out at the end and looking forward to my next matches."

It sets up a match with countryman Karen Khachanov, who defeated Britain's Jack Draper in a 6-4 6-2 straight sets victory of his own at Memorial Drive Tennis Centre.

Japan's Yoshihito Nishioka will also compete in the quarter-finals after a 6-4 6-3 win over American Mackenzie McDonald, and will face home favourite Alexei Popyrin.

At the Tata Open Maharashtra in Pune, top seed Marin Cilic needed to survive a second-set fightback from Spain's Roberto Carballes Baena before he progressed 6-3 3-6 6-1.

Aslan Karatsev meanwhile took a two-set thriller against Tim van Rijthoven, prevailing in a 7-6 (9-7) 7-6 (10-8) triumph.

Novak Djokovic is set to miss the Indian Wells Open and Miami Open after the United States extended the requirement for all non-American nationals to be vaccinated against COVID-19.

The 21-time grand slam winner was forced to sit out both tournaments last year, as well as other events in America and Canada, due to not being vaccinated.

Whereas many countries are relaxing vaccination requirements, meaning Djokovic is able to compete in this year's Australian Open, US travel authorities are asking for proof of being fully vaccinated against coronavirus to enter the country until at least April 10.

That will see Djokovic sit out the prestigious Indian Wells between March 6 and March 19, and the Miami Open between March 20 and April 2.

Djokovic is currently competing in the Adelaide International, where he kicked off his season with a 6-3 6-2 win over Constant Lestienne on Tuesday, ahead of beginning his quest for a 10th Australian Open crown later this month.

The Serbian was deported from Australia this time last year after his visa was revoked due to his unvaccinated status and was initially banned from entering the country for three years, but that was waived in November.

Aryna Sabalenka secured a straight-sets win in her first match of 2023, but was made to work for it by Liudmila Samsonova at the Adelaide International.

The number two seed won 7-6 (10-8) 7-6 (7-3), saving seven set points after going 5-1 down in the first set, before roaring back to take both tie-breaks.

Sabalenka will face Marketa Vondrousova in the quarter-finals, with the Czech having produced a dominant performance in a 6-0 6-4 win against Kaia Kanepi. 

"When it's 1-5 down, it's like you have nothing to lose, and you just go for your shots without thinking," Sabalenka said.

"That really helped me to stay in the set, to keep fighting and to keep trying."

Fourth seed Veronika Kudermetova eased through after a 6-4 6-0 victory against Bianca Andreescu, while Marta Kostyuk also advanced with a hard-fought 6-7 (5-7) 6-2 6-3 win over Elena Rybakina.

At the ASB Classic in Auckland, second seed Sloane Stephens is out after falling to Rebeka Masarova.

Having been forced to resume on Wednesday after rain suspended play the previous day, Stephens struggled against her Spanish opponent, eventually losing 6-3 7-6 (7-5).

Fifth seed Wang Xiyu is also out after retiring from her match against Karolina Muchova, but seventh seed Danka Kovinic is through after a simple 6-1 6-4 win against Nao Hibino.

Kovinic will face Lauren Davis next after she overcame Tamara Zidansek 6-2 6-1, while fellow American Sofia Kenin will take on number one seed Coco Gauff in the last 16 after she beat Wang Xinyu in straight sets.

Wins for Hubert Hurkacz and Magda Linette saw Poland advance to the City Finals of the United Cup in Australia on Tuesday.

Hurkacz made it through a tough encounter against Stan Wawrinka 7-6 (7-5) 6-4 to give Poland a 2-1 lead in their Group B tie with Switzerland in Brisbane, before Linette came from behind to beat Jil Teichmann 5-7 6-4 6-1 to clinch it.

Poland will face Italy in the Brisbane final, whose 5-0 whitewash of Norway included Matteo Berrettini sealing victory with a 6-4 6-4 win over Casper Ruud.

In Perth, Croatia advanced to the City Finals after a dramatic day that saw Caroline Garcia get France on the board with a straight sets win against Petra Martic, before Adrian Mannarino came from a set down against Borna Gojo to serve for the match as he looked to bring his country level at 2-2.

However, Gojo broke back in a tense encounter before winning a deciding tie-break to send Croatia through to face Greece, who sealed a 4-1 win against Belgium.

Stefanos Sakellaridis recovered from going a set behind to beat Zizou Bergs, before Maria Sakkari overcame Elise Mertens 6-1 7-5, with Sakkari and Stefanos Tsitsipas adding some gloss to the score with a mixed doubles success against Kirsten Flipkens and Michael Geerts. 

Spain and Australia were unable to progress but the hosts at least had the consolation of securing a victory thanks to wins for Jason Kubler against Albert Ramos-Vinolas, and the mixed doubles duo of John Peers and Sam Stosur against Jessica Bouzas Maneiro and David Vega Hernandez.

The USA had already secured their Finals berth against Great Britain in Sydney, but were ruthless as they finished off their tie against Germany to win 5-0.

After Jessica Pegula beat Laura Siegemund 6-3 6-2, Frances Tiafoe also defeated Oscar Otte in straight sets, before the American duo combined to beat Siegemund and Daniel Altmaier 6-7 (5-7) 6-4 10-7 to complete a clean sweep.

Boris Becker has swiftly found work after his release from prison, with the German tennis great signed up for television commentary during the Australian Open.

The six-time grand slam singles champion, who took the Australian title in 1991 and 1996, will be part of German Eurosport's team for the season's opening grand slam.

That was announced by the broadcaster on Tuesday, with Becker to co-commentate on big matches and present a 'Matchball Becker' analysis segment twice a day.

Becker, 55, has worked for Eurosport in previous years, as well as being a regular on the BBC's coverage of Wimbledon, a tournament he won three times.

He was released from jail in December, eight months into a two-and-a-half-year sentence handed down as punishment for hiding £2.5million worth of assets and loans to avoid paying debts when he was declared bankrupt in 2017.

Becker, a former coach of Novak Djokovic, reportedly spent the first few weeks of his sentence at Wandsworth Prison in London before being moved to the low-security Huntercombe prison in Oxfordshire in May.

In an interview with Sat.1 after his release, Becker spoke of his experience, saying: "When the cell door closes, the whole world collapses. This is the loneliest moment I've ever had.

"There is only you with your thoughts. There's a carousel in your head, of course. You try to breathe calmly. I was afraid, I didn't cry.

"I believe I rediscovered the human in me, the person I once was. I've learned a hard lesson. A very expensive one. A very painful one."

Novak Djokovic took just an hour and 15 minutes to win his first singles match in Australia since 2021, beating Constant Lestienne 6-3 6-2 at the Adelaide International on Tuesday.

Djokovic – who saw a three-year visa ban lifted in November – played with Vasek Pospisil in the doubles on Monday, but this was his first singles outing in the country since his vaccine-related absence from last year's Australian Open.

"For the first match [of the season] I can't complain," Djokovic said. "I played very well. I thought the first six games were very competitive and I have never faced him before.

"But once I made that break at 3-2 in the first set I thought I stepped it up and played really good tennis for the rest of the match."

Elsewhere in Adelaide, third seed Daniil Medvedev advanced after Lorenzo Sonego retired hurt with the Russian leading by a set, while sixth seed Jannik Sinner eased past Kyle Edmund 6-3 6-2.

Seventh seed Denis Shapovalov is also through after coming from a set down to beat Rinky Hijikata, but fourth seed Andrey Rublev is out after losing to Roberto Bautista Agut in three sets.

The Spaniard will face Sebastian Korda next after he beat Andy Murray 7-6 (7-3) 6-3, while eighth seed Karen Khachanov advanced after beating Pedro Cachin 6-2 6-4. 

At the Maharashtra Open in Pune, Aslan Karatsev had no problems seeing off Pablo Andujar 6-1 6-3, with the eighth seed set to face Tim van Rijthoven in the last 16 after the Dutchman beat Radu Albot 6-4 6-4.

There were also wins for Maximilian Marterer against Elias Ymer and Pedro Martinez against Ramkumar Ramanathan.

Emma Raducanu and Coco Gauff both got off to winning starts at the ASB Classic in Auckland on Tuesday.

Raducanu had to come from a set down to beat Linda Fruhvirtova 4-6 6-4 6-2, while top seed Gauff had an easier time of it as she dismissed Tatjana Maria 6-4 6-1 on another day interrupted by the rain.

Second seed Sloane Stephens was only able to get through three games before play was suspended in her match against Rebeka Masarova, while fifth seed Wang Xiyu was 5-3 down in the first set against Karolina Muchova when the rain came.

Fourth seed Bernarda Pera is out after her match with Viktoria Kuzmova resumed having being washed out on Monday, and the American was unable to prevent a 6-4 6-4 defeat, with Kuzmova advancing to face Raducanu in the last 16.

The only two other matches completed on Tuesday saw Elena-Gabriela Ruse beat Erin Routliffe in three sets, and Anna Blinkova overcome Elisabetta Cocciaretto, also in three.

At the Adelaide International, Zheng Qinwen earned a hard-fought victory against number six seed Anett Kontaveit, eventually winning 6-1 4-6 7-6 (9-7).

Eighth seed Ekaterina Alexandrova also crashed out despite winning the first set against Marketa Vondrousova, going on to lose 4-6 6-3 6-2, though seventh seed Jelena Ostapenko is through after beating Karolina Pliskova 6-1 6-3.

In a contest that lasted over two-and-a-half hours despite only two sets being played, Victoria Azarenka beat Anhelina Kalinina 7-6 (11-9) 7-6 (7-5), and will face Zheng next, while Sorana Cirstea will go up against top seed Ons Jabeur in the last 16 after beating Viktorija Golubic in straight sets.

Chris Evert has backed her long-time rival and friend Martina Navratilova to win her latest cancer battle.

American tennis great Evert, who completed her own course of chemotherapy treatment in May after being diagnosed with ovarian cancer, said Navratilova's "strength and resilience" would stand her in good stead.

Navratilova has been diagnosed with throat and breast cancer, she announced on Monday. The Czech-American successfully underwent treatment for breast cancer in 2010 and has said the condition is "serious but still fixable" this time.

Evert's battles with Navratilova in the 1970s and 1980s provided one of the all-time great tennis rivalries.

Both women ended their careers with 18 grand slam singles titles, with Navratilova triumphing a record nine times at Wimbledon. Only Steffi Graf (22) and Serena Williams (23) have won more singles majors among women in the Open Era.

Evert posted on Twitter: "Thinking of @Martina today and supporting her journey, like she did mine, with love and prayers. This is a woman who takes on challenges with strength and resilience…You got this, Martina."

Former US Open champion Tracy Austin sent "prayers and hugs", adding: "Don’t know too many stronger, I know you got this my friend."

Navratilova's long-time former doubles partner Pam Shriver added: "@Martina knows how to put together a winning team. While the news today is difficult, Martina understands how to compete, and take care of herself.

"Her loving family and many friends are ready to support her journey one day at a time. You have this partner!"

Ons Jabeur, who was runner-up at Wimbledon and the US Open last season, said she was "sending my love and my support".

Martina Navratilova said she is "not done yet" after it was confirmed she had been diagnosed with throat and breast cancer.

Navratilova is one of the most decorated tennis players of all time, having won 18 grand slam singles titles between 1978 and 1990.

She successfully underwent treatment for breast cancer in 2010, but it has been revealed she is once again battling the illness.

A representative described Navratilova's prognosis as "good", and the 66-year-old said the disease was "serious but still fixable".

Navratilova has pledged to fight, posting on Twitter: "Needless to say my phone and Twitter are both blowing up.

"I will say again – thank you all for your support and I am not done yet."

The Czech also received support from Billie Jean King, who tweeted: "Martina is as brave as she is strong. She has fought this battle before, and she is in our thoughts and prayers."

Billie Jean King insists Martina Navratilova is "as brave as she is strong" after the latter was diagnosed with throat and breast cancer.

Navratilova is one of the most decorated players of all time, having won 18 grand slam titles during a glittering career.

The 66-year-old underwent successful treatment for breast cancer in 2010, but it has now been confirmed she is battling the illness again.

Navratilova said the diagnosis is "serious but still fixable," while a representative confirmed she will start treatment later this month and subsequently not attend the Australian Open.

King, a 12-time major winner, offered her support.

"Martina is as brave as she is strong," the 79-year-old tweeted.

"She has fought this battle before, and she is in our thoughts and prayers."

Rafael Nadal is "not too alarmed" about suffering back-to-back losses ahead of the Australian Open following his latest United Cup defeat.

The Spaniard suffered a second successive reverse in Sydney, going down 3-6 6-1 7-5 to Alex de Minaur after falling to Cameron Norrie.

Nadal is set to go in search of a record-extending 23rd grand slam title later this month, having won in Melbourne in 2022.

Yet the 36-year-old is not getting hung up on his form, instead taking the losses as learning curves.

"I have two weeks before the Australian Open starts," he said. "I can't say the situation is ideal, but I can't say it's negative.

"I was playing good. I need hours on court, I need battles like this. Days like these two help. I need to keeping fighting.

"I'm not too alarmed, too negative about what happened. I think it was a real chance to lose these kinds of matches."

Nadal won the first set against De Minaur, and was a game away from victory in the decider before succumbing to a comeback.

"Alex played better in the crucial moments. That made the difference," Nadal said.

"I had my chances to win, but I made costly mistakes when I could not afford them. You can not win a match like this while doing that."

Martina Navratilova has been diagnosed with throat and breast cancer, though a representative described the prognosis as "good".

Navratilova won 18 grand slam singles titles between 1978 and 1990, making her one of the most decorated players of all time.

She underwent successful treatment for breast cancer in 2010, but it has now been confirmed she is battling the illness again.

Navratilova said: "This double whammy is serious but still fixable, and I'm hoping for a favourable outcome.

"It's going to stink for a while but I will fight with all I have got."

Navratilova, 66, was due to travel to Melbourne this month to work on coverage of the Australian Open, a tournament she won three times.

But with her treatment due to start later in January, it has been confirmed she will not be in attendance.

A statement from a representative explained: "The prognosis is good and Martina will start her treatment this month.

"The cancer type is HPV and this particular type responds really well to treatment.

"Martina noticed an enlarged lymph node in her neck during the WTA finals in Fort Worth. When it didn't go down, a biopsy was performed, the results came back as stage one throat cancer.

"At the same time as Martina was undergoing the tests for the throat, a suspicious form was found in her breast, which was subsequently diagnosed as cancer, completely unrelated to the throat cancer.

"Both these cancers are in their early stages with great outcomes.

"Martina won't be covering the Australian Open for Tennis Channel from their studio but hopes to be able to join in from time to time by Zoom."

Novak Djokovic was beaten in his first match back in Australia but did at least receive a warm reception from the crowd at the Adelaide International.

Djokovic – who saw a three-year visa ban lifted in November – was playing with Vasek Pospisil in the doubles, and the duo lost 4-6 6-3 10-5 to Tomislav Brkic and Gonzalo Escobar on Monday, but the fans in attendance chanted "Novak" as they welcomed him back following his absence from last year's Australian Open.

The Serbian will face Constant Lestienne in the first round of the men's singles, but second seed Felix Auger-Aliassime is already out after he lost to Alexei Popyrin.

Auger-Aliassime struggled throughout as his Australian opponent, ranked 120th in the world, put in a crowd-pleasing performance to go through 6-4 7-6 (7-5).

Another young star, Holger Rune, is also out after the fifth seed was beaten 2-6 6-4 6-4 by Yoshihito Nishioka.

Quentin Halys set up a potential second-round clash with Djokovic after beating Jordan Thompson in straight sets, while Miomir Kecmanovic, Jack Draper, Roman Safiullin and Thanasi Kokkinakis all progressed.

It was also a bad day for seeds at the Maharashtra Open in Pune, with Alex Molcan beaten 6-2 6-4 by Laslo Djere and Jaume Munar losing 6-4 7-5 to Tallon Griekspoor.

Dutchman Griekspoor will now play Marco Cecchinato after the Italian overcame Nikoloz Basilashvili, and Roberto Carballes Baena set up a last-16 clash against top seed Marin Cilic by defeating fellow Spaniard Bernabe Zapata Miralles.

Filip Krajinovic did make it through a tussle with home favourite Sumit Nagal to set up a meeting with Michael Mmoh, while Benjamin Bonzi will face third seed Emil Ruusuvuori after beating Tseng Chun-hsin.

Rafael Nadal suffered his second defeat in as many matches after going down 3-6 6-1 7-5 against Alex de Minaur at the United Cup.

The 22-time grand slam champion, who was also beaten by Great Britain's Cameron Norrie in his opening match, is still seeking his first victory of the season with the Australian Open just around the corner.

Home favourite De Minaur delighted the Sydney crowd by recovering from a set and break down to claim his maiden win over the world number two.

"I think it's definitely up there [as one of my best wins]," he said. "It's one of those achievements that you have unlocked in your career.

"But also, it's a big win for myself, one that I really needed. I'm going to cherish and use, take all the confidence from this and be able to hopefully take it to have a good [Australian] summer."

Spain and Australia are unable to progress to the City Finals, but Nuria Parrizas Diaz levelled the Group D tie with a 6-1 6-3 victory over Maddison Inglis.

The USA, who required just two points against Germany to advance to the next stage, set up a showdown with Great Britain after Taylor Fritz and Madison Keys enjoyed straight-set successes over Alexander Zverev and Jule Niemeier respectively. 

Italy moved to the brink of joining them in the City Finals after taking a 2-0 lead over Norway. Lorenzo Musetti overcame Viktor Durasovic in straight sets, while Martina Trevisan edged out Malene Helgo in three.

Greece require one win from their final three matches against Belgium to also advance, Stefanos Tsitsipas hit 12 aces on the way to defeating David Goffin 6-3 6-2 to level the Group A showdown at 1-1.

Poland's winner-takes-all Group B clash with Switzerland is also finely poised at 1-1. World number one Iga Swiatek beat Belinda Bencic 6-3 7-6 (7-3), before Marc-Andrea Huesler's 6-3 6-2 victory against Daniel Michalski.