Four-time grand slam champion Naomi Osaka has announced she is pregnant and is not expecting to play tennis again until next year.

The 25-year-old has not been in action since September and withdrew from the upcoming Australian Open on Sunday, but no reason was given for her prolonged absence.

However, Osaka revealed on her personal social media accounts on Wednesday that she is expecting her first child and will take a year out.

"Can't wait to get back on the court, but here's a little life update for 2023," she wrote alongside an image of an ultrasound. 

"The past few years have been interesting to say the least, but I find that it's the most challenging times in life that may be the most fun. 

"These few months away from the sport have really given me a new love and appreciation for the game I've dedicated my life to.

"I realise that life is so short and I don't take any moments for granted, every day is a new blessing and adventure. 

"I know that I have so much to look forward to in the future, one thing I'm looking forward to is for my kid to watch one of my matches and tell someone, 'that's my mom,' haha.

"2023 will be a year that'll be full of lessons for me, and I hope I'll see you guys at the start of the next one 'cause I'll be at Aus 2024. Love you all infinitely."

The Japanese former world number one won the Australian Open in 2019 and 2021, while also winning the US Open in 2018 and 2020.

Osaka is currently ranked 42nd in the world and has been replaced by Dayana Yastremska in the main draw for the opening grand slam of the year.

"I don't think there's a perfectly correct path to take in life," Osaka added in her post. "But I always felt if you move forward with good intentions you'll find your way eventually."

Danielle Collins needed seven match points to defeat Jil Teichmann at the Adelaide International 2 but ultimately progressed to the quarters.

Collins, seeded 10th, had victory in her grasp after reeling off four straight games in the second set.

Yet she was unable to get over the line at the first six times of asking, initially failing to serve out the win before Teichmann saved five match points.

Collins, though, regained momentum in the tie-break to win 6-3 7-6 (7-2).

World number nine Veronika Kudermetova is next up for Collins, having received a walkover to the last eight.

Caroline Garcia, the highest-ranked player left in the tournament, overcame Katerina Siniakova 6-3 3-6 7-5, but was made to work for her win.

Having been pegged back in the second set, Garcia seemed well set to push for victory when she went 3-1 up in the decider, but Siniakova broke and then held her serve to restore parity.

A tie-break looked likely until Garcia converted the third break point of a thrilling 12th game to claim victory.

Barbora Krejcikova, the 2021 French Open champion, was ousted by fifth seed Daria Kasatkina, who cruised through 6-2 7-5.

World number eight Kasatkina will take on two-time Wimbledon champion Petra Kvitova for a place in the last four.

Belinda Bencic also progressed, as did Paula Badosa and Beatriz Haddad Maia.

Anna Blinkova caused an upset at the Hobart International, dispatching top seed Marie Bouzkova 7-5 6-4.

Fifth seed Anhelina Kalinina is the favourite after Bouzkova's exit and a tie with 2019 champion Sofia Kenin is her reward for a win over Tatjana Maria. 

Paula Badosa savoured a strong serving day as she overcame Anett Kontaveit in a tricky Adelaide International 2 opener ahead of the Australian Open.

Badosa and Kontaveit both got as high as number two in the world rankings last year, but neither currently sits in the top 10, with Badosa down at number 11 and Kontaveit 17th.

Tuesday's tussle in South Australia went the way of the Spaniard, with Badosa scoring a 6-4 6-3 win against her Estonian opponent.

She had five aces and only one double fault, winning 77 per cent of points when landing a first serve in.

Another Estonian awaits her at the last-16 stage in veteran campaigner Kaia Kanepi and Badosa is happy with how she had begun the tournament.

"I think I started really good," Badosa said in an on-court interview. "I was serving very well. I was going for the first shots."

Asked about signs of improvement with her serve, Badosa said: "It depends on the day, to be honest. I worked a lot this past 10 days and was really focused on that, so I'm happy about that."

Czech Barbora Krejcikova, another player with a career-high ranking of number two, earned a second-round shot at Russian Daria Kasatkina after winning 6-2 7-6 (7-3) against last year's runner-up Alison Riske-Amritraj.

Other winners in Adelaide on Tuesday were Amanda Anisimova, Zheng Qinwen, Veronika Kudermetova, Anna Kalinskaya and Katerina Siniakova.

At the Hobart International, second seed Elise Mertens fell 6-4 6-4 to fellow Belgian Maryna Zanevska, while French third seed Alize Cornet was also knocked out, losing 6-4 6-2 to Italy's Elisabetta Cocciaretto.

Former Australian Open champion Sofia Kenin had no such trouble, seeing off China's Zhu Lin 6-2 6-2

Petra Kvitova defeated Elena Rybakina in the pick of the first-round matches at the Adelaide International 2 on Monday.

Two-time Wimbledon winner Kvitova hit 21 winners to 12 unforced errors on her way to a 6-3 7-5 win against reigning SW19 champion Rybakina in a match lasting 87 minutes.

Belinda Bencic, a defeated finalist in this tournament in 2021, also advanced with a 6-3 6-4 win against former world number one Garbine Muguruza to maintain her positive form.

Fellow seeded players Beatriz Haddad Maia and Danielle Collins beat Sorana Cirstea and Karolina Pliskova respectively to book their places in the last 16.

At the Hobart International, favourite Marie Bouzkova saw off Jacqueline Cristian 7-6 (7-2) 6-3, while Lauren Davis defeated Sloane Stephens 6-2 6-2 in an all-American clash.

Aryna Sabalenka warmed up for the Australian Open by winning her first WTA title since May 2021 as she beat Linda Noskova in the Adelaide International 1 final on Sunday.

Sabalenka lost in all three of her final appearances in 2022, but she began 2023 in emphatic fashion and crowned a fine week with a 6-3 7-6 (7-4) triumph.

Noskova, who at 18 years and 43 days old became the youngest finalist of a WTA 500-level or above event since 2008, looked up for a scrap as both players threatened to break in the early stages.

But Sabalenka soon took the initiative with the match's first break to go 4-2 up thanks to a ferocious backhand, and she subsequently cruised to seal the set.

The teenager kept things tighter for much longer in the second and went close to tying the match as she found herself 5-4 up and at deuce.

But a tiebreak beckoned, and Noskova's pair of double faults helped Sabalenka open a 5-1 lead, eventually seeing out the win at the second time of asking with a powerful serve that gave her young opponent too much to do.

Sabalenka clinched her success without dropping a single set over the course of the week, something she will hope provides a springboard as she aims to improve on her previous best at the Australian Open, where she reached the fourth round in 2021 and 2022.

Coco Gauff won the third WTA title of her career as she warmed up for the Australian Open by sweeping past Rebeka Masarova in the final of the ASB Classic.

The 18-year-old was too good for Masarova throughout in Auckland, easing to a 6-1 6-1 victory in just an hour and 15 minutes on Sunday.

Gauff forced a break point in Masarova's first service game, and though the Spanish-Swiss player was able to rescue it, she was not so lucky in her next two as her ruthless opponent won the first set with back-to-back breaks.

That theme continued in the second as unforced errors from Masarova, who won just two out of 15 points on her second serve (13.3 per cent), saw Gauff break again immediately.

The American was then forced to save break points on her own serve but did so impressively as she rescued all 10 against her in the contest.

Masarova was able to get on the board again after saving another two break points, but that was as good as it got, with ultimately Gauff romping to victory in front of an impressed New Zealand crowd.

"It's been a great week for me, despite the rain," Gauff said, referring to tournament's frequent weather disruption, which also delayed the final and forced a pause at the end of the first set.

"It's my first title on hard [court] since I was 15, so I'm happy to do well on a surface that I love.

"It gives me a lot of confidence [ahead of the Australian Open]. You're never sure how your first week is going to go, but it's been a great week."

Four-time major champion Naomi Osaka has withdrawn from the 2023 Australian Open.

The 25-year-old Japanese is a two-time Australian Open winner (2019 and 2021), but tournament organisers confirmed on Sunday she will not be adding to that tally in 2023.

No reason has yet been cited for Osaka's decision, although she has not played since pulling out of the Pan Pacific Open in Tokyo in September.

Osaka endured a difficult 2022 at grand slams, losing in the first round at both the French Open and US Open, while she was bundled out in the third round of last year's Australian Open and did not compete at Wimbledon due to an Achilles injury.

The former world number one's withdrawal follows that of men's top seed Carlos Alcaraz and seven-time major winner Venus Williams due to injury. 

Reigning women's singles champion Ash Barty has also since retired following her triumph in January last year.

Osaka is currently ranked 42nd in the world and will be replaced by Dayana Yastremska in the main draw.

Lucia Bronzetti downed Valentini Grammatikopoulou to seal Italy's place in the final of the inaugural United Cup.

Despite losing to Poland in their City Final in Brisbane, Italy claimed a place in the Sydney play-offs as the best-placed runner-up.

Having led 2-0 overnight, Italy were pegged back by Stefanos Tsitsipas' battling 4-6 7-6 (7-2) 6-4 win over Matteo Berrettini.

That put the pressure on Bronzetti's meeting with world number 199 Grammatikopoulou.

Yet despite losing her two previous matches against Grammatikopoulou, world number 54 Bronzetti made no mistake, cruising to a 6-2 6-3 victory.

Italy will now face the United States, who beat Poland 5-0 in their semi-final, in the final on Sunday.

Coco Gauff marched into ASB Classic final with an emphatic defeat of Danka Kovinic, while Linda Noskova upset Ons Jabeur to set up an Adelaide International showdown with Aryna Sabalenka.

Gauff beat Kovinic 6-0 6-2 to move into her first hard-court final since claiming the title in Linz back in October 2019.

The top seed from the United States won the first eight games of a one-sided semi-final, making another statement just over a week before the Australian Open gets under way.

Gauff took only 73 minutes to dispatch seventh seed Kovinic and will face qualifier Rebeka Masarova in the final on Sunday.

Spaniard Masarova reached her first WTA Tour final courtesy of a 6-3 6-3 victory over Ysaline Bonaventure.

The 130-ranked Masarova, a junior French Open singles champion in 2016, served with assurance and struck 16 winners to break new ground.

It was also a memorable Saturday for Czech teenager Noskova, who claimed the scalp of world number two Jabeur with a 6-3 1-6 6-3 victory in Adelaide.

It was the 18-year-old Noskova's second win over a top-10 opponent this week, having also knocked out Daria Kasatkina.

Second seed Sabalenka will be a strong favourite to deny world number 102 Noskova the title on Sunday after she saw off Irina-Camelia Begu 6-3 6-2.

Venus Williams has withdrawn from the Australian Open due to injury and Iga Swiatek's participation could be in doubt.

The American was given a wildcard for the first grand slam of the year, but suffered an injury setback at the ASB Classic this week.

Williams was beaten by Zhu Lin of China in the second round of the tournament in Auckland on Thursday and it was revealed on Saturday she will not play at Melbourne Park.

The 42-year-old, who has shown incredible longevity in her illustrious career, is a seven-time grand slams singles champion and winner of 14 major doubles titles.

Williams won four of her grand slam doubles crowns at the Australian Open and lost her two singles finals in 2003 and 2017.

Australian Kim Birrell has been awarded Williams' wildcard place nine days before the tournament gets under way.

Meanwhile, world number one Swiatek has withdrawn from the Adelaide International 2 next week due to a shoulder injury.

Swiatek was in tears after she was beaten by Jessica Pegula while representing Poland against the United States in the United Cup on Friday.

Iga Swiatek was in tears after losing to Jessica Pegula as the United States took a 2-0 United Cup semi-final lead over Poland, while Italy moved into command against Greece on Friday.

World number one Swiatek was beaten 6-2 6-2 by the impressive Pegula in just 71 minutes at Ken Rosewall Arena.

Swiatek got the better of Pegula three times last year, but the American made light work of seeing off the three-time grand slam champion this time around to put USA in front.

Pegula struck 21 winners, attacking the Swiatek serve in a commanding display just over a week before the Australian Open gets under way.

Swiatek's emotions came out after she was emphatically defeated by the world number three in Sydney.

Pegula said: "I played her today, conditions are totally different than anywhere else I played her. Obviously maybe I had a little bit of an advantage, they just flew in yesterday.

"Definitely the fastest conditions I have played her [in]. Every other place I've played her has been pretty slow. I think that favoured me a lot, and I was able to use that to my advantage and play a really super clean match.

"I think I just was able to execute my game plan probably better than I have previous times."

Frances Tiafoe backed up Pegula's win by beating Kacper Zuk, who replaced the unwell Daniel Michalski, 6-3 6-3.

That ensures Taylor Fritz has a chance to put the United States into the final if he beats Hubert Hurkacz on Saturday.

Italy are in control of the other semi-final following victories for Martina Trevisan and Lorenzo Musetti.

Trevisan upset Maria Sakkari 6-3 6-7 (4-7) 7-5 before Musetti outclassed Stefanos Sakellaridis, winning 6-1 6-1.

Former world number one Ash Barty has revealed she is pregnant with her first child.

Barty surprisingly announced her retirement from tennis last March, just two months after she ended a 44-year wait for a home triumph at the Australian Open.

The 26-year-old, who won three grand slam singles titles during her career, revealed her pregnancy via an Instagram post on Friday.

"2023 set to be the best year yet. We are so excited for our new adventure. Origi already the protective big sister," Barty wrote, alongside an image of her dog Origi next to a pair of baby shoes. 

Barty's partner Garry Kissick also took to social media to share the news, posting a similar image featuring a baby-sized Liverpool kit with the caption: "Little Red, 2023".

Barty married professional golfer Kissick last July, six years after the pair met at the Brookwater Golf Club in 2016.

In addition to last year's Australian Open, Barty enjoyed singles success at Wimbledon in 2021 and the French Open in 2019, as well as winning the women's doubles title at the 2018 US Open alongside CoCo Vandeweghe.

Teenage Czech qualifier Linda Noskova upset former world number one Victoria Azarenka to set up a semi-final showdown with Ons Jabeur at the Adelaide International.

In a match lasting almost three hours, Noskova triumphed 6-4 6-7 (3-7) 7-6 (8-6) to continue a dream run in Australia.

Noskova has already beaten third seed Daria Kasatkina in Adelaide and, on only her sixth appearance in a WTA main draw, has won five straight matches.

Further progress will be no easy feat, with top seed Jabeur – a losing finalist at Wimbledon and the US Open in 2022 – grinding out a 7-6 (7-5) 7-5 win over Ukrainian Marta Kostyuk.

On the other side of the draw, second seed Aryna Sabalenka held off a resurgent Marketa Vondrousova to win 6-3 7-5. The Belarusian had led 4-1 in the second set before losing four of the next five games and failing on match point prior to finally seeing it out.

Irina-Camelia Begu defeated fourth seed Veronika Kudermetova 7-5 6-4 to set up a last-four clash with Sabalenka.

At the ASB Classic in Auckland, top seed Coco Gauff outclassed Zhu Lin 6-3 6-2, winning 90 per cent of first-serve points, firing down eight aces, and not giving up a single break point.

Seventh seed Danka Kovinic also won 6-3 6-2 against Viktoria Kuzmova to set up a semi-final clash with Gauff, while world number 95 Ysaline Bonaventure ousted third seed Leylah Fernandez 6-4 6-2 to reach a first Tour-level semi-final where Rebeka Masarova awaits.

Emma Raducanu was in tears as she retired with an ankle injury at the ASB Classic 11 days before the Australian Open starts, while Coco Gauff beat Sofia Kenin to reach the quarter-finals.

Raducanu dished out a bagel to qualifier Viktoria Kuzmova in the first set of the round of 16 match in Auckland on Thursday, but the 2021 US Open champion was unable to continue after losing the second set 7-5.

The 20-year-old Brit ended a disappointing 2022 season early due to a wrist injury and suffered another blow ahead of the first major of this year, leaving the court in tears.

Gauff will be eyeing her maiden grand slam title in 2023 and she impressively dispatched fellow American Kenin 6-4 6-4 in the second round in the capital of New Zealand.

Top seed Gauff and her compatriot were forced to play indoors due to the rain and it was the 18-year-old who prevailed, breaking three times and saving six of the break points she faced.

The teenager will face Zhu Lin of China for a place in the semi-finals after she beat Venus Williams 3-6 6-2 7-5.

Leylah Fernandez inflicted a crushing 6-0 6-1 defeat on Julia Grabher after losing only two games in her first-round win over Brenda Fruhvirtova and the Canadian will now face Ysaline Bonaventure, who defeated Rebecca Marino in three sets.

Top seed Ons Jabeur made a winning start to the season at the Adelaide International, seeing off Sorana Cirstea 7-6 (7-3) 6-1 to set up a meeting with Marta Kostyuk

Irina-Camelia Begu claimed the scalp of Jelena Ostapenko with a 6-3 6-0 upset of the seventh seed, while Victoria Azarenka was a 6-2 7-5 winner against Zheng Qinwen and teenager Linda Noskova got past Claire Liu in straight sets.

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.