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.

Linda Noskova produced the biggest win of her career as she defeated Daria Kasatkina 6-3 6-7 (2-7) 6-3 at the Adelaide International on Monday.

The 18-year-old Czech was impressive against the third seed as she recorded her first win against anyone in the top 30 of the world rankings.

Fourth seed Veronika Kudermetova eased past Amanda Anisimova in just an hour and 15 minutes, winning 6-3 6-0, while Liudmila Samsonova will face second seed Aryna Sabalenka in the next round after coming from a set down to beat Zhang Shuai 5-7 6-3 6-0.

Irina-Camelia Begu and Elena Rybakina also both came from behind to secure wins, with the latter beating fifth seed Danielle Collins to set up a last-16 clash against Ukrainian Marta Kostyuk, who beat Jaimee Fourlis 6-1 3-6 6-4.

At the ASB Classic in Auckland, 42-year-old Venus Williams comfortably overcame her 21-year-old opponent Katie Volynets 7-6 (7-4) 6-2, and will play China's Zhu Lin next after she eliminated sixth seed Madison Brengle 4-6 7-6 (8-6) 6-4.

Third seed Leylah Fernandez beat Brenda Fruhvirtova 6-1 6-1 to set up a last-16 tie with Julia Grabher after she defeated Tereza Martincova in three sets.

Eighth seed Rebecca Marino is through after beating Dalma Galfi in straight sets and will now face Ysaline Bonaventure, who eventually put away Caty McNally 5-7 6-4 6-4.

Viktoria Kuzmova led fourth seed Bernarda Pera 5-4 in the opening set when rain stopped play for the day.

Roger Federer saluted Iga Swiatek's miracle shot at the United Cup, declaring 'that was crazy' in response to a tweet from the world number one.

Swiatek - the winner of eight WTA titles in 2022 including the French Open and US Open - helped Poland to a commanding 4-1 victory over Kazakhstan in their opening match in Brisbane.

With the Poles' first win in the competition secure, the 21-year-old helped Hubert Hurkacz put the icing on the cake with a 6-3 6-4 success in their mixed doubles clash against Zhibek Kulambayeva and Grigoriy Lomakin.

Swiatek's moment of brilliance came at 30-15 in game six. Desperately chasing Lomakin's drop volley after a fiercely contested rally, she produced a wonderful backhand slice around the net post to the amazement of everyone inside the Pat Rafter Arena.

The shot was executed on several occasions by 20-time grand slam champion Federer, who retired last year, including in his third-round clash with Nick Kyrgios at the 2018 US Open.

Swiatek subsequently asked the Swiss in a light-hearted tweet: "Do you approve?" - to which he replied: "That was crazy."

The world number one is back in action on Monday when Poland ironically face Switzerland, who boast the likes of Olympic gold medallist Belinda Bencic and three-time grand slam winner Stan Wawrinka in Group B.

Dan Evans helped Great Britain reach the last eight of the inaugural United Cup as his 6-3 1-6 6-3 win over Albert Ramos-Vinolas decided the team's Group D tie against Spain.

Rafael Nadal's shock defeat to Cameron Norrie – coupled with Katie Swan's win against Nuria Parrizas-Diaz – put Spain 2-0 down in the best-of-five tie ahead of Sunday's action.

World number 13 Paula Badosa put them back into contention with a hard-fought 6-7 (6-8) 7-6 (7-5) 6-1 win against Harriet Dart, but Evans gave Britain an unassailable lead by battling past Ramos-Vinolas, recovering from a dismal second set.

Having topped Group D, Britain will face the Croup C winners – the United States, Germany or the Czech Republic – for a semi-final place on Wednesday.

Meanwhile, Hubert Hurkacz doubled up to help Poland past Kazakhstan, teaming up with Iga Swiatek in the mixed doubles after beating Alexander Bublik.

Hurkacz beat Bublik 7-6 (8-6) 4-6 6-3 in just over two hours before Magda Linette overcame Zhibek Kulambayeva 6-2 6-1.

With Poland's first win in the competition secure, world number one Swiatek helped Hurkacz put the icing on the cake with a 6-3 6-4 victory against Kulambayeva and Grigoriy Lomakin.

The Czech Republic also enjoyed a fruitful day as two-time Wimbledon champion Petra Kvitova downed Laura Siegemund in straight sets to seal the team's win against Germany, but Casper Ruud was less fortunate, with Norway losing their tie against Brazil despite his success against Thiago Monteiro.

Iga Swiatek warned rivals "I'm getting stronger and stronger in my mind" as she targets another memorable season in 2023.

The world number one enjoyed a dominant 2022 as she landed eight titles, including the French Open and US Open, while also embarking on a 37-match winning streak – the longest this century on the WTA Tour – and registering 22 'bagel' sets.

Swiatek made a winning start to her 2023 campaign at the United Cup with Poland earlier in the week, beating Kazakhstan's Yulia Putintseva 6-1 6-3 in Brisbane.

While acknowledging she must not become complacent this year and rely on past glories, the 21-year-old feels better prepared for the season with the Australian Open just a fortnight away.

"I feel more solid, and I feel more stability as well because last year, Adelaide was my first tournament with a new coach [Tomasz Wiktorowski], so that was my main focus," she said.

"This year, I have totally different challenges, so it's really hard to compare. But I feel like I had more time to actually work on some technical stuff at home, and hopefully I'm going to be able to use it in matches.

"I just think that it's going to be pretty easy for my head to compare everything to last year. And I feel like it's not really going to be helpful.

"Last year, it wasn't perfect, but sometimes when you win tournaments, all your head can remember is those good moments and that it went so smoothly.

"It wasn't like that, but I don't really want to go into those tournaments and be held back by my previous results. I want to treat it as new chapters, so I'm going to try to do that.

"But this is the biggest challenge I'd say, and we'll see how I'm going to go with that. Usually when I had goals like that, I had ups and downs, but I feel like I'm getting stronger and stronger in my mind, so maybe I'm going to be able to control that."

Wimbledon's ban on Russian and Belarusian players taking part last year was unjust and changed nothing regarding the war in Ukraine, believes Aryna Sabalenka.

Following Russia's invasion of Ukraine last February, the Lawn Tennis Association (LTA) barred players from both countries appearing at SW19 – a decision that saw the organisation fined by the ATP last month.

World number five Sabalenka joined the likes of Daniil Medvedev, Andrey Rublev and Victoria Azarenka in being excluded, and she believes the ban was both unfair and pointless.

"This is really terrible because no one supports war – no one," Sabalenka told The Age of the ban. "I'm just really disappointed sport is somehow in politics. 

"We're just athletes playing their sport. That's it. We're not about politics. If all of us could do something [about the war], we would do it, but we have zero control.

"They banned us from Wimbledon, and what did it change? Nothing. [The Russian government] are still doing this, and this is the sad part of this situation."

The LTA is yet to say whether similar measures will be in place this year, and Sabalenka is hopeful of a return after missing the atmosphere at SW19 in 2022.

"I really missed the people because the atmosphere at Wimbledon is super amazing," she said. "You can feel these people really love tennis there, and I really miss them.

"I really hope that I'll play there, just because of the people, to feel this atmosphere. If they're going to ban us again... I don't care about Wimbledon's decision. The only thing I'll miss is the people."

Rafael Nadal shot down questions over his potential retirement after losing to Cameron Norrie at the United Cup, saying he is "here to continue playing tennis".

As part of his preparation for next month's Australian Open, 22-time grand slam winner Nadal fell to a 3-6 6-3 6-4 defeat to Norrie as Great Britain seized a 2-0 lead over Spain in Sydney.

Norrie had not won a set against Nadal in their previous four matches, and the 36-year-old was asked afterwards how much longer he planned to continue before calling it a day on his historic career.

"Every time I come to a press conference, it seems like I have to retire," Nadal told reporters. "You're very, very interested in my retirement.

"At the moment, that's not the case. When this day comes, I'll let you know.

"But don't go on the subject of retirement because I'm here to continue playing tennis."

With just over two weeks until Nadal's Australian Open title defence gets underway, the Spaniard knows he will have to improve on his performance against Norrie, saying: "I need to be faster physically and a little more solid.

"There is a way to improve, but I have time before the Australian Open starts in two weeks."

While Nadal's shaky performance against Norrie could cause concern over whether he can defend his crown in Melbourne, he was keen to credit the British number one, stating: "He is a top player.

"He didn't impress me much because I know he is very good. He did a lot of things well, very solid, without mistakes, serving well. I can do things better and I need to."

Nadal will be in action again at the United Cup on Sunday, taking part in a doubles match with Paula Badosa against Daniel Evans and Harriet Dart.

Rafael Nadal's United Cup campaign began with defeat against Cameron Norrie as Great Britain established a 2-0 lead over Spain in Group D.

The 22-time grand slam winner surrendered a first-set lead before going down 3-6 6-3 6-4 against the world number 14, who secured his first victory in five meetings.

Norrie, who became only the second Briton after Andy Murray to beat the Spaniard, set the tone for his team, with Katie Dart also coming from behind to deny Nuria Parrizas Diaz 3-6 6-1 6-2 later on.

Meanwhile, Germany's Alexander Zverev lost in straight sets on his return to ATP action, going down 6-4 6-2 to Jiri Lehecka of the Czech Republic, who went 2-0 up in the tie after Marie Bouzkova defeated Jule Niemeier 6-2 7-5.

World number one Iga Swiatek got Poland off to a flying start against Kazakhstan in Brisbane with a commanding 6-1 6-3 victory over Yulia Putintseva, but defeat for Daniel Michalski against Timofey Skatov leaves the Group B tie finely poised.

Brazil enjoyed a flawless start against Norway in Group E. Beatriz Haddad Maia was a 6-4 6-2 winner over Malene Helgo, and Felipe Meligeni Alves overcame Viktor Durasovic 6-3 6-3.

The spoils were shared between Belgium and Bulgaria in Group A with Alison van Uytvanck beating Isabella Shinikova, before David Goffin was seen off by Grigor Dimitrov 6-4 7-5.

Croatia closed the day with a pair of victories against Argentina in Group F as Donna Vekic and Borna Coric defeated Maria Carle and Francisco Cerundolo respectively.