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."

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."

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.

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'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.

Maria Sakkari sealed victory for top-seeded Greece over Bulgaria in the United Cup with a straight sets win over Viktoriya Tomova.

Team-mates Stefanos Tsitsipas and Despina Papamichail had already won their matches on Thursday, and Sakkari's 6-3 6-2 triumph gave Greece an unassailable 3-0 lead.

Michail Pervolarakis was defeated by Dimitar Kuzmanov in the final singles match between the nations, but Tsitsipas and Sakkari teamed up to earn Greece a 6-4 6-4 success in the doubles encounter to end on a high.

World number 16 Matteo Berrettini helped Italy topple Brazil by overcoming Thiago Monteiro 6-4 7-6 (9-7).

That gave Italy a 2-1 lead, and Lucia Bronzetti finished the job by demolishing Laura Pigossi in straight sets, with Brazil powerless to overturn the deficit despite Berrettini and Camilla Rosatello's defeat in the doubles match.

US Open semi-finalist Frances Tiafoe clinched a win for the United States over the Czech Republic after opponent Tomas Machac retired with an ankle injury with the score at 6-3 2-4.

Petra Kvitova had defeated Jessica Pegula 7-6 (8-6) 6-4 in the third singles match to give Czech Republic hope, but Tiafoe's win settled the contest before Pegula and Taylor Fritz joined up for success in the doubles.

Great Britain were 3-2 victors over Australia despite a pair of defeats on day two in Sydney.

Cameron Norrie's triumph over Nick Kyrgios' replacement Alex De Minaur on day one had helped Great Britain to a 2-0 lead over the hosts, and Harriet Dart prevailed over Maddison Inglis to wrap up the victory.

Dan Evans was then beaten 6-3 7-6 (7-3) by Jason Kubler before Dart and Jonny O'Mara fell to defeat in the doubles, but Great Britain's strong start saw them through.

France and Switzerland completed 5-0 sweeps of Argentina and Kazakhstan respectively, with Caroline Garcia winning both her singles and doubles matches in straight sets while Stan Wawrinka saw off Alexander Bublik 6-3 7-6 (7-3).

Nick Kyrgios accused Australia co-captain Lleyton Hewitt of throwing him "under the bus" following his decision to withdraw from the United Cup.

The 2022 Wimbledon finalist, who has been struggling with an ankle injury, was due to line up alongside the likes of Alex De Minaur and Jason Kubler in the inaugural edition of the team event.

However, Kyrgios surprised team-mates with his decision to pull out of the event, with the 27-year-old switching his focus to achieving full fitness for next month's Australian Open.

Hewitt was unaware of Kyrgios' withdrawal until his public announcement and said he needs to improve his communication skills.  

Kyrgios' withdrawal was followed by that of Ajla Tomljanovic, who pulled out of her match against Great Britain's Harriet Dart due to a knee injury.

Kyrgios responded to a Twitter post about the news, questioning whether co-captain Sam Stosur would respond the same way Hewitt did.

"Mmm I wonder if Stosur will throw her under the bus like our captain did for me... 'hard to prepare when you don't know what's going on'," Kyrgios wrote.

Australia suffered a 3-2 defeat to Great Britain in their Group D meeting, although they will have another chance to progress to the knockout stage when they face Spain next week.

Stefanos Tsitsipas opened his United Cup campaign with a comeback victory over Grigor Dimitrov in Perth.

ATP world number four Tsitsipas is one of the headline names in action at the event, which is acting as a warm-up tournament for the Australian Open.

After going a set down to his Bulgarian opponent in his first game of the inaugural tournament, Tsitsipas hit back with a strong second set before holding his nerve in a tense tie-break in the decider, securing a 4-6 6-2 7-6 (7-4) win.

Tsitsipas's team-mate Despina Papamichail continued Greece's strong start, also coming from a set down to beat Isabella Shinikova 3-6 6-4 6-1.

Great Britain opened with a pair of victories, Cameron Norrie and Katie Swan earning straight sets triumphs over their Australian counterparts in Sydney.

Norrie, who was initially set to play Nick Kyrgios prior to the Wimbledon finalist's withdrawal due to an ankle injury, eased to a 6-3 6-3 victory over Alex De Minaur, while Swan defeated Zoe Hives. 

The United States are also taking a 100 per cent record into day two of the tournament, after Taylor Fritz and Madison Keys overcame Jiri Lehecka and Marie Bouzkova respectively, while France pair Arthur Rinderknech and Alize Cornet got off to winning starts against Argentina's Francisco Cerundolo and Maria Lourdes Carle.

In Brisbane, Swiss hope Belinda Bencic secured a 7-6 (7-0) triumph over Yulia Putintseva of Kazakhstan and Beatriz Haddad Maia, the Brazilian world number 15, dispatched Italy's Martina Trevisan 6-2 6-0.

Nick Kyrgios has withdrawn from the United Cup on the eve of the inaugural edition of the tournament, with Australia team captain Samantha Stosur admitting "it's news to all of us."

The 2022 Wimbledon finalist, who has been struggling with an ankle injury, was due to line up alongside the likes of Alex De Minaur and Ajla Tomljanovic in the new team event.

However, Kyrgios surprised team-mates with his decision to pull out of the event, in which Australia face Great Britain in their opening match on Thursday, reportedly switching his focus to achieving full fitness for next month's Australian Open.

"I'm not going to speak for Nick’s summer, we've got to leave that for him," Stosur said at a press conference. "He was here. We literally just found out 10 minutes ago, so it's obviously news to all of us.

"But we just move forward now. We're all happy to be here and keen to get out there. Now that's out there, and we move forward with the placings of the team and do our best on the day.

"As far as the men's side of this team goes, we're in very capable hands still, so I'm not concerned that our chances have just diminished greatly or anything like that. We're out here to do everything we can possible to try and win this competition."

De Minaur added: "We've all just heard. Ultimately, we're just going to get ready. We’ve got a great team, and we're all going to be out there doing our best. So ultimately, the only thing that changes is match-ups and that's about it."

Tennis icon Venus Williams will compete in her 22nd Australian Open in January after it was announced on Sunday she had been awarded a wildcard entry.

Williams, 42, is a seven-time grand slam singles champion, but she only played four competitive matches in 2022, losing all four.

A five-time Wimbledon winner with two US Open titles on the singles side, Williams is also one of the sport's most decorated doubles players, collecting another 14 grand slam doubles titles, including four in Australia.

She won the Australian Open doubles in 2001, 2003, 2009 and 2010, while making the singles final in both 2003 and 2017.

In the press release announcing her wildcard, Williams confirmed her plans to compete once again in Melbourne.

"I am very excited to be returning to Melbourne to compete at the Australian Open in January," she said.

"I've been competing in the country for over 20 years now and the Australian community has always supported me wholeheartedly.

"It will be an honour to play for the fans again and I'm looking forward to making more memories at the tournament this year."

It remains to be seen if she will be joined by her sister, Serena, who is a seven-time singles champion at the event and Venus' partner for her four doubles successes.

After her exit from the US Open, Serena heavily implied she was weighing up another go down under, saying "I always did love Australia".

Emma Raducanu is working with a new coach as she heads towards the 2023 season, reports said on Friday.

The 2021 US Open winner, who turned 20 in November, has had a growing list of coaches and is seeking the right formula to make an alliance successful.

She has turned for now to German Sebastian Sachs, a 30-year-old who previously worked with Victoria Azarenka, as a member of the Belarusian's team, before becoming the main coach of Julia Goerges and latterly Belinda Bencic.

Olympic champion Bencic recently appointed Dmitry Tursunov, who had been working with Raducanu, and Sachs has headed in the opposite direction by joining up with the British youngster.

As well as Russian former ATP top-20 player Tursunov, Raducanu has had coaching spells under the tutelage of Nigel Sears, Andrew Richardson, Torben Beltz and the Lawn Tennis Association's Iain Bates in the past two years.

Raducanu and her team have yet to formally announce Sachs' role, but reports have indicated he has been with her this week in Abu Dhabi. Her management have yet to confirm whether this is a trial or a full-time appointment.

The one-time grand slam winner had a match on Friday against Ons Jabeur at the Mubadala World Tennis Championship, an exhibition event, losing 5-7 6-3 10-8 to the 2022 Wimbledon and US Open runner-up.

After parting company with Raducanu, Tursunov said getting the best out of the Briton would be "minimum a one-year project but... probably a two-and-a-half-year project to be on the safe side", and reasoned that her game remained "very raw".

"It's going to take some time, but as I said to her and to pretty much everyone on her team: I think you just need to have one voice and just try that for a bit," Tursunov said.

Raducanu has not reached a final since her dazzling Flushing Meadows victory, and she finished the 2022 season at 76th in the WTA rankings.

Serena Williams may return to the court "one more time," former world number two Tommy Haas believes.

The 23-time grand slam singles champion Williams declared her intention to "evolve" away from tennis prior to the US Open in September, with many thinking her third-round defeat to Ajla Tomljanovic signalled the end of her illustrious career.

Although, the 41-year-old hinted she may return in a recent interview with Jimmy Fallon, suggesting she may follow the example of another American sporting great.

"Tom Brady started an amazing trend," she said when asked if her competitive career may resume. "That's what I want to say."

Speaking to Eurosport Germany's tennis podcast Das Gelbe vom Ball, Haas said: "Serena had an incredible, long and strong career. 

"But I have the feeling that she is going to come back and say, 'I'm going to play one more time.' 

"She came so close to playing really well again and going far, so I think deep down it really annoys her.

"She might really be thinking about whether she wants to try again. I may be wrong because I'm not that close [to her].

"It will mostly depend on how it looks mentally, how she feels physically and whether she has the desire to torture herself like that again after achieving so much."

Carla Suarez Navarro has announced she is pregnant, with the Spanish former tennis star who overcame cancer expressing her "tremendous joy" and "great pride."

Now 34, Suarez Navarro was diagnosed with Hodgkin lymphoma in September 2020, just months after announcing her intention to retire.

She delayed that retirement and, after being given the all-clear in April 2021, began a farewell tour at that year's French Open that included appearances at Wimbledon, the US Open, the Olympic Games and the Billie Jean King Cup.

Having left competitive tennis behind at the end of the 2021 season, Suarez said she and her partner Olga Garcia were thrilled to announce the pregnancy, with their baby due in June.

Garcia, 30, is a footballer who has played for the Barcelona, Atletico Madrid and Spain women's teams.

They said in a shared statement on Instagram: "A new stage that we really wanted to experience. Let's grow the family! Excited and happy to face this big moment. Very soon we will be one more."

Both were showered with messages of congratulations and love, from the likes of Manchester United goalkeeper David de Gea and tennis names including Caroline Wozniacki, Garbine Muguruza, Paula Badosa and Sara Errani.

Suarez Navarro explained, in a statement reported by Spanish media: "We wanted to announce that I am three months pregnant. It's already 12 weeks of tremendous joy to bring a new life into the world.

"Both Olga Garcia, my partner, and I feel an enormous responsibility, a great pride for having taken this step, and we were excited to share it with all of you.

"This Tuesday, we went to perform the first trimester ultrasound, to verify that the pregnancy is progressing on the right track. Fortunately, the medical team has confirmed that the gestation process is developing completely normally.

"It is fantastic news for us and fills us with hope for the near future."

The former WTA player, who reached a career-high world ranking of sixth, added: "After my retirement from sports, with both of us still young, we thought it was the ideal time to face a process that fills us with joy and enthusiasm.

"We are very excited with what we are going through and with all the experiences that we hope to live soon."