Emma Raducanu has hit back "unfair" criticism over her mounting sponsorship deals following her early exit from the Miami Open.

The US Open champion was beaten by Katerina Siniakova in her first match in Miami this week after being given a bye into the second round.

Raducanu has only won four WTA Tour matches since she was sensationally crowned champion at Flushing Meadows as a qualifier in New York last September.

The 19-year-old has been in demand off the court and last week revealed she will be a brand ambassador for Porsche.

Briton Raducanu insists she is still driving high standards in training as she strives to build on her maiden grand slam triumph.

"Maybe you just see, on the news or on social media, me signing this or that deal and I feel like it’s quite misleading because I’m doing five, six hours a day [in training], I’m at the club for 12 hours a day," the 19-year-old told reporters.

"But I throw out one post in the car on the way to practice and all of a sudden it’s 'I don't focus on tennis'. I think that it is unfair, but it's something I have learned to deal with and become a bit more insensitive to the outside noise.

"At the end of the day, I feel like my days [with sponsors] are pretty limited. I'm not doing crazy days. I'm doing three, four days every quarter, so it's really not that much."

New world number one Iga Swiatek says taking the top rank is a "dream come true" and something she never strongly believed could happen.

Swiatek made history as the first Polish tennis player to reach the top ranking, taking over the mantle following Ashleigh Barty's shock decision to retire from the sport in midweek. She will officially become number one when the WTA rankings are updated on April 4.

The 20-year-old Pole, who won the 2020 French Open and made this year's Australian Open semi-finals, made the ascent to the summit after beating Viktorija Golubic 6-2 6-0 at the Miami Open on Friday.

"It's a dream come true, for sure," Swiatek told reporters. "It's that kind of thing that I wanted to happen someday, but I didn't really know that it's going to be possible for me.

"I never really imagined that moment, because truth to be told, I was working day by day and I was playing tennis well, but I never had that like that strong belief that it can actually happen, so it's even more surreal for me."

Swiatek has claimed WTA 1000 titles at Indian Wells and Doha this year, with her victory over Golubic extending her winning run to 12 matches.

She is the 28th woman to reach the summit in the WTA rankings, becoming the youngest player at the top since Caroline Wozniacki in 2010.

"I think it's going to be a bit different and maybe the hype is going to be a bit bigger, but I'm ready for that," she said.

"Honestly, it's like part of the job, so I always knew if I'm going to succeed, it's going to be there. I really appreciate people being really enthusiastic and really pumped up because I think sometimes I'm even playing for them."

Barty was quick to congratulate Swiatek on claiming the number one ranking, saying there is "no better person" than the Pole.

"There is no better person," Barty said in a message. "The way that she's brought this fresh, fearless energy onto the court has been incredible.

"I hope she can take it and still be her, do it her own way, and really chase what she's after in her career and her dreams."

Fifth seed Andrey Rublev has been eliminated from the Miami Open in the second round in straight sets by wild card world number 102 Nick Kyrgios on Friday.

The enigmatic Australian triumphed 6-3 6-0 in 52 minutes to clinch a third round clash with Italian Fabio Fognini, who won in three sets against Japanese Taro Daniel.

The victory marks Kyrgios' third win over a top 10 opponent in the past two tournaments, having topped both Casper Ruud and Jannik Sinner at Indian Wells earlier this month.

Rublev had won titles in Marseille and Dubai earlier this season but was not allowed to settle by Kyrgios who sent down 10-5 aces and had a first serve percentage of 80 per cent.

"I know that he's a player who relies on a bit of rhythm, so I just tried to keep the points short and sharp, just play aggressive," Kyrgios said after the match.

"I'm just happy with my performance, whether it's 7-6 in the third or something like this, I'm just happy to get through."

Second seed Alexander Zverev was made to work for victory against Croatian Borna Coric, winning 6-4 3-6 6-3 in two hours and one minute.

The win marks the 2018 Miami Open runner-up's first triumph at the event since that run to the final.

Sixth seed Ruud eased past Henri Laaksonen 6-1 6-2, while ninth seed Sinner defeated Emil Ruusuvuori 6-4 3-6 7-6 (10-8) in two hours and 40 minutes.

Several seeds were beaten included 13th seed Diego Schwartzman who went down 4-6 7-6 (7-3) 6-4 to Thanasi Kokkinakis. Seeds Lorenzo Sonego, Grigor Dimitrov, Reilly Opelka and John Isner also exited.

Gael Monfils defeated Oscar Otte 7-6 (11-9) 6-1, Pablo Carreno Busta won 6-3 6-2 over David Goffin and 10th seed Cameron Norrie won 7-6 (7-5) 6-4 over Jack Draper.

Former French Open champion Iga Swiatek has risen to world number one in the wake of Ashleigh Barty's retirement with a 6-2 6-0 win over Viktorija Golubic at the WTA Miami Open on Friday, sealing her ascent.

Swiatek, who won recent WTA 1000 events this year at Indian Wells and Doha, cruised to victory in one hour and 14 minutes over the Swiss.

The 20-year-old Pole, who won the French Open in 2020 and reached this year's Australian Open semi-finals, will officially become the top-ranked player when the rankings are updated on Monday April 4.

Barty's name will be removed from the rankings at her request having announced her shock retirement earlier this week at the age of 25, despite winning this year's Australian Open and last year's Wimbledon titles.

Swiatek is the 28th woman to reach the summit in the WTA rankings, becoming the youngest player at the top since Caroline Wozniacki in 2010. She will become Poland's first-ever number one in tennis history.

The Pole extended her winning streak to 12 matches against Golubic, taking her to a tour-high 21 wins this year, in a match where she saved eight of nine break points and took six of the nine she generated.

Swiatek's main immediate competition for the top rank was fifth seed Paula Badosa who got past Marie Bouzkova 7-5 7-5 in two hours and three minutes.

Badosa, who got the edge by grinding out games under pressure, will face Yulia Putintseva in the third round after she won 6-3 4-6 7-5 over Lesia Tsurenko.

Fourth seed Maria Sakkari was bundled out of contention following a shock 4-6 6-1 6-2 loss to Brazilian Beatriz Haddad Maia.

Two-time major winner Petra Kvitova needed three sets to get past Clara Burel, winning 6-1 3-6 6-3 in one hour and 45 minutes.

Jessica Pegula beat Sloane Stephens 6-1 6-4, Cori Gauff got past Qiang Wang 7-5 6-4 and 20th seed Elise Mertens went down 7-5 2-6 6-1 to Linda Fruhvirtova.

Naomi Osaka is through to the third round of the Miami Open after beating former world number one Angelique Kerber in straight sets.

Osaka won the first three games of the match to jump out to an early lead, securing the set with a double-break before breaking early in the second to cruise to a 6-2 6-3 win.

The story of the match was Osaka's ease in winning points against Kerber's serve, winning 41 per cent (15/37) of Kerber's successful first serves, while the German could only win 11 per cent (3/27) in the same category.

Britain's top-ranked woman Emma Raducanu suffered another early exit, on the wrong end of Katerina Siniakova's comeback 3-6 6-4 7-5 win.

Daniil Medvedev will have to go through two-time Miami Open champion Andy Murray to quickly reclaim the world number one ranking.

Medvedev's first stint at the top of the ATP rankings ended swiftly when he lost in the third round at the Indian Wells Masters and was displaced by Novak Djokovic.

But the Russian has the opportunity to leapfrog Djokovic once more by making the semi-finals in Miami.

Before thinking about the latter stages of the Masters 1000 tournament, however, Medvedev first must master Murray, who looked in good nick on his return to Miami.

Murray has twice won this tournament but has not played it since 2016, meaning Thursday's match against Federico Delbonis was his Hard Rock Stadium debut.

Delbonis had won the pair's only prior meeting yet was outclassed 7-6 (7-4) 6-1 after a steady first set.

Medvedev and Murray have also only met once before now, with the world number two coming out on top, but the wild card is looking forward to the challenge.

"It's a big challenge for me, a big test," Murray said. "I've got a big training block after this tournament and it'll be a really good test for where my game's at and the things I need to work on as well against him. I'm looking forward to that."

That is not the only mouthwatering second-round tie, with Nick Kyrgios through to face Andrey Rublev.

However, Stefanos Tsitsipas has a slightly more straightforward task on paper after qualifier J.J. Wolf advanced past Daniel Altmaier.

Simona Halep has withdrawn from the Miami Open after aggravating a thigh injury.

Former world number one Halep was due to face Australia's Daria Saville in the round of 64 on Thursday but felt unable to contest the match.

Halep said she sustained a thigh injury during her Indian Wells semi-final defeat to Iga Swiatek the previous week and it caused her discomfort again while training on Wednesday.

The 30-year-old two-time major winner expects to sit out the Charleston Open and will miss the start of the Billie Jean King Cup.

In a tweet posted on her official Twitter account, Halep wrote: "While I was practising in Miami yesterday I felt a sharp pain in my left leg.

"I had been struggling with the thigh since my semi-final in Indian Wells and hoped it would improve, but I went for an MRI last night and unfortunately it showed a tear.

"My body needs time to heal and as a result I will be out of competition for three weeks. This means I have had to make the super tough decision to pull out of Miami, Charleston and Fed Cup [Billie Jean King Cup].

"While it feels like really disappointing news to share, I am keeping the confidence from my great start to the year and am motivated to do everything to be ready for the clay-court season.

"Thanks for your continued support through the highs and lows."

Lucky loser Harmony Tan will take Halep's place in the draw.

Naomi Osaka looked relaxed and composed as she eased to a straight-sets win at the Miami Open, and offered a clue as to why when speaking to reporters afterwards.

The 24-year-old revealed she has started seeing a therapist after her recent loss at Indian Wells, where she suggested a heckler had affected her performance.

Osaka was left in tears as she struggled to deal with someone apparently shouting "Naomi, you suck!" during her second-round defeat to Veronika Kudermetova.

She also withdrew from Roland Garros last year, citing mental health concerns.

However, the three-time grand slam champion produced a strong display in her first round encounter in South Florida to beat Astra Sharma 6-3 6-4 on Wednesday.

"I don't know if I'm allowed to say this, but I finally started talking to a therapist after Indian Wells. It only took like a year after French Open," she told reporters after her win.

"She kind of told me strategies and stuff. I realise how helpful it is. I'm glad that I have people around me that told me to, like, go in that direction.

"But, yeah, I was basically just remembering all the things that she told me to do, just to take deep breaths and reset myself when I need to."

The world number 77 revealed it was partly her sister, former professional player Mari Osaka, showing concern that led her to seek out therapy.

"I feel like I've been trying a lot of different things because I tend to internalize things, and I also want to do everything by myself," Osaka clarified, adding that her coach, Wim Fissette, had also encouraged her to do so.

Osaka believes she is now better prepared to handle a similar situation to Indian Wells should it arise, having realised it may have been the first time she has been heckled during a game.

"I think for me, the situation in Indian Wells, I've kind of thought back on it. I realise I've never been heckled. I've been booed, but not like a direct yell-out kind of thing. It kind of took me out of my element.

"I feel like I'm prepared for it now. I was kind of bracing myself before the match to just know that's a thing that could happen now. I think I just needed to change my mindset a little."

Ash Barty has not ruled out a return to professional tennis, saying "never say never" when asked if she could make a comeback in years to come.

The three-time grand slam winner announced her surprise retirement from the sport on Wednesday, less than two months after her home victory at the Australian Open.

At just 25, Barty is stepping away from the court at the peak of her career, and has teased the idea she could step into another sport entirely.

But speaking on Thursday, the reigning Wimbledon champion did not discount the possibility of returning to tennis down the line.

"You never say never," she said. "But it's a long way off at this stage."

Barty previously played cricket during a sabbatical between 2014 and 2016, and has been linked with a switch to golf in recent years too.

She shut down such suggestions as an immediate option, adding: "[I've] got to try and learn how to hit the middle of the club face before I can think of trying to get on the tour."

Elsewhere, Barty admitted that she would miss the competition of the WTA circuit, while praising fellow Australian Open champion Rafael Nadal for his staying power in the sport.

"I love the competition," she said. "That's what has driven me the most in my career, is that one-on-one competition and the thrill of the fight. I know that I'll miss it 100 per cent.

"But I'll be able to get the adrenaline in different ways. Those ways will remain to be seen. But I know that I've been so fortunate to have so many incredible moments on the court."

Unlike Nadal, Barty is bowing out of tennis early, and she respects the way the 35-year-old Spaniard, who also triumphed at Melbourne Park this year, has been able to stay at the top for the best part of two decades.

She said: "It's been an incredible career. His longevity in the sport has been undeniable. He's been amazing for the sport of tennis. For me as a fan to see him do that over such an extended period has been a pleasure."

Ash Barty insisted she would "never stop loving" tennis as the three-time grand slam winner kept everyone guessing about her next steps in life.

The 25-year-old announced a shock retirement on Wednesday, less than two months after triumphing at the Australian Open.

Barty hinted she would look to find a new role in sport, possibly in a playing capacity, and said she and boyfriend Garry Kissick had set a wedding date, but left it at that.

Speaking at a news conference in Brisbane, Barty said she had intended to reveal her retirement after playing for Australia in a Billie Jean Cup qualifying match in April.

However, reigning champions Russian Tennis Federation were recently excluded, due to the war in Ukraine, which meant the event was restructured and Australia did not need to play a qualifying tie. Barty consequently brought her announcement forward.

She said she had "given absolutely everything I could to this sport", and confirmed she has asked the WTA to remove her name from the world rankings the next time they are published.

Barty has retired as the world number one, with Iga Swiatek in pole position to succeed her. Results at the Miami Open, getting under way this week, will determine who tops the list when it is released on April 4.

"It's going to be an exciting time for the WTA Tour with the new number one," she said. "It will be a really cool period for them now."

Australian Barty, who is also the reigning Wimbledon champion, said of her career: "It's been a hell of a journey. I wouldn't change a thing and I certainly have no regrets."

She said winning the Australian Open in January had been "a brilliant way to finish", adding: "I'm excited for what's next, for my next chapter as Ash Barty the person, not Ash Barty the athlete."

Appearing alongside coach Craig Tyzzer, Barty said she had been practising on court even in the last fortnight.

"I hit as recently as 10 days ago," she said. "I'll forever be connected to tennis. I'll never stop loving the sport, I'll never stop hitting tennis balls. I just won't be doing it selfishly to progress my career, it'll be for different reasons."

Barty has played cricket at a high level before and is a keen golfer.

So could she look for a career in a sport other than tennis?

"I've seen some brilliant Photoshops as a jockey, lawn bowls," she said. "I love sport. I'm a sport nut, like a lot of Australians are; I'll be glued to it.

"I've always been an athlete in a sense of trying different things. But we will see how we go."

She is eager to share her tennis knowledge with youngsters in a coaching capacity, and appears to be relishing a quiet life away from the hustle of being a globe-trotting sports star.

Asked about her plans to marry Kissick, a trainee club golf professional, Barty said plans were in place, adding: "You have to wait and see."

Nick Kyrgios maintained his impressive form from Indian Wells to prevail in his first-round match with Adrian Mannarino at the Miami Open.

Former world number 13 Kyrgios is ranked outside the top 100, but delivered a reminder of his quality at Indian Wells by reaching the quarter-finals.

He claimed a top-10 win over Casper Ruud before losing to Rafael Nadal in three sets, and the Australian will now face Andrey Rublev in South Florida after seeing off Mannarino in straight sets.

Kyrgios took the first in a tie-break and broke the Mannarino serve late in the second to clinch a 7-6 (7-3) 6-3 win.

There was a huge disparity in the winner count, Kyrgios hitting 33 to Mannarino's 15, and it was that extra firepower that made the difference in the closing stages.

A fine backhand winner gave Kyrgios break point, which he converted with a confident forehand at the end of an absorbing rally to take a 5-3 lead. The break was then consolidated as Kyrgios sealed his triumph with an ace down the middle.

Also into the second round is Jack Draper, who overcame Gilles Simon to claim his first ATP Masters 1000 win and set up an all-British clash with Cameron Norrie.

Brandon Nakashima will meet American compatriot Frances Tiafoe after his first main-draw win in Miami over Soonwoo Kwon.

Thanasi Kokkinakis beat Richard Gasquet in straight sets while there were also wins for David Goffin and Borna Coric.

US Open champion Emma Raducanu is not planning on replicating Ash Barty after the world number one retired at the age of 25.

Barty announced her retirement on Wednesday less than two months after winning the Australian Open, saying she has accomplished all she set out to in the sport.

There has since been an outpouring of respect and admiration for Barty, with the prevailing sentiment being that it is a great loss for tennis.

Raducanu burst onto the scene last year with a run to the fourth round at Wimbledon that was followed by a remarkable triumph at Flushing Meadows, making history at the age of 18 in becoming the first player to win a grand slam as a qualifier in the Open Era, doing so without dropping a set.

And she is planning on staying on the WTA Tour for many years to come.

"For me, I want to be in the game as long as possible," Raducanu said.

"I'm only 19. I've just come on tour, which is pretty young.

"I want to be in the game till I'm in my 30s. We'll see what happens and how long I can last, to be honest."

Reflecting on Barty's career, one in which she took a break from the sport in 2014, briefly playing professional cricket, before returning in 2016, Raducanu added: "If you get oversaturated with one thing, it's not healthy with anything you do.

"I feel like that just shows, if you take time off, you come back, you're hungry, you're ready. 

Two of the top-ranked players on the WTA tour have spoken about world number one Ash Barty's shock retirement, with Danielle Collins calling it "badass".

Barty announced she had retired through a post on her Instagram account, where she had a sit-down interview with former Australian tennis player Casey Dellacqua about her decision to walk away.

In her interview, Barty discussed accomplishing the goals she set out for herself in her tennis career, capped off with wins at Wimbledon and this year's Australian Open, as well as having other dreams she would like to work towards.

Barty, 25, has played professional cricket in Australia's Big Bash League, and has been linked with her beloved Richmond Tigers if she were to try her hand at Australian Rules football.

She is also recently married, and has discussed her desire to start a family.

Collins, currently the world number 11, spoke about how incredible it is that Barty is able to walk away at such a young age, with so many accomplishments under her belt.

"I am a little bit surprised because I think at 25 and being at the top of her game and in achieving everything that she's achieved and being so young she would certainly continue to achieve what she's been achieving," Collins said.

"But I think it really speaks to the way that our game empowers women, because how many other professions would you be able to retire at 25? 

"I mean, this is incredible, it's so badass, and I really have a lot of respect for Ash making the decision to do what's best for her, and to live out her life on her terms. It's really special."

Rising star and world number two Iga Swiatek also weighed in, saying her first reaction was an outpouring of emotion about what a loss it was for the game of tennis.

"Well, I mean, it is so fresh and it's so sudden that it is something that I need to digest," the 20-year-old said.

"I cried for like 30 minutes, actually, when she posted that video and that interview. 

"It's very hard to describe it because on one hand… if you know Ash, it's not a surprise at all, because she's like that kind of person who's looking for challenges also in other aspects of life. 

"I mean, you can see that she's pretty confident with her decision. But on the other hand, it's new for me to see athletes retiring so early. 

"I'm pretty new on tour and I feel like I wanted to play more matches against Ash, and also compete against her and have a chance to actually understand how she plays and how she uses the different skills that she has. 

"I mean, for me, I feel kind of sad that I'm not going to be able to do that because I think it would be a great rivalry. And also, she's a great person to look up to and to kind of chase. 

"But I'm also happy for her, and I think she's really brave that she made that decision because there would be many people who, I don't know, kind of stay in this place because you were first in the world. 

Naomi Osaka moved to extinguish the painful memories from Indian Wells as she eased into the second round of the Miami Open.

The three-time grand slam champion, who was left in tears as she struggled to deal with a heckler during her second-round defeat to Veronika Kudermetova at Indian Wells, produced a composed display in South Florida to see off Astra Sharma 6-3 6-4.

Needing an hour and 20 minutes to defeat her Australian opponent, Osaka secured her 50th WTA 1000 win, one that sets up a battle of two former world number ones.

Osaka will next face Angelique Kerber, having kept her cool against Sharma despite converting just two of 11 break point opportunities and squandering three match points.

"I didn't want to let anything bother me, no matter what happened," Osaka said.

"The last match I played was not the greatest memory for me. I wanted to prove that I could come back out here and compete, and no matter if I won or lost, to just know that I had the best attitude I could."

Kerber promises to prove a much sterner test for Osaka, who has lost her last four matches against the German, having won their first encounter at the 2017 US Open.

Osaka's Japanese compatriot Misaki Doi crashed out in a straight-sets defeat to Vera Zvonareva, while promising teenager Clara Tauson retired in the third set of her match with Zhang Shuai.

Madison Brengle was among those to progress on Wednesday, continuing the theme of early American success.

You don't know what you've got until it's gone.

That is how tennis fans the world over will be feeling after women's world number one Ash Barty shockingly announced her retirement on Wednesday.

Barty noted that achieving a lifelong goal of winning Wimbledon last year and being "spent physically" were motivating factors behind her decision.

The 25-year-old bows out on top having lifted her home slam at the Australian Open back in January, and is a three-time singles major champion.

Following news of her retirement, Stats Perform has delved into some of Barty's best facts from a stellar career.

SECOND ONLY TO OSAKA IN SLAMS SINCE 2016

There have been 14 different singles grand slam champions in a stacked women's game since 2016.

In that time, Barty has women three major titles – the second most alongside Angelique Kerber. Indeed, the only player to have more in the women's game over that period is Naomi Osaka with four.

Barty retires on a 13-match winning streak (all on hard courts), a run that of course includes her triumph at the Australian Open.

It matches the best run of her career, with Barty proving 13 is not unlucky for all by racking up the same amount of wins on clay and grass between May and June 2019 – that stretch having seen her lift her first slam at the French Open.

KVITOVA A FAMILIAR FOE

Barty has mixed it with the best in the women's game but she has faced no player more than two-time Wimbledon champion Petra Kvitova.

She has faced the Czech on 10 occasions, with the two sharing five wins apiece. Barty has also beaten Sofia Kenin, Karolina Pliskova, Shelby Rogers and Kiki Bertens on five occasions.

Caroline Wozniacki (3) and Mona Barthel (2) are the only players Barty has faced more than once but never beaten in women's tennis.

Conversely, Barty has defeated each of Marketa Vondrousova, Camila Giorgi, and Saisai Zheng four times from as many attempts, her most matches against any players against whom she has maintained a 100 per cent win rate.

STILL GOING STRONG

Never has the saying "always leave them wanting more" been truer than in the case of Barty.

She has averaged seven aces per match in women's tennis in 2022, the joint-most of any player alongside China's Qinwen Zheng and Hailey Baptiste of the United States.

Barty has made 77 aces in total in 2022, the joint-sixth most of any player but 30 fewer than WTA leader Madison Keys (107).

Moreover, she has won 94 per cent of service games, the highest rate of any player and eight percentage points higher than second-ranked Elena Rybakina of Kazakhstan.

Barty won 71 per cent of her points when serving this calendar year, the highest rate of any player and four percentage points higher than second-most Rybakina.

Indeed, Barty did not lose a match in her shortened 2022 season, finishing 11-0 and winning 25 of her final 26 matches. 

114 WEEKS AND OUT

Barty is the second female player to step away from the game when ranked world number one, with Justin Henin having done so in 2008 after 61 consecutive weeks at the top.

Barty does so having racked up 114 straight weeks at the summit of the rankings, a run which represents the fourth longest in the history of the WTA Tour behind only Steffi Graf (186 weeks), Serena Williams (186) and Martina Navratilova (156).

Her accumulated total of 121 weeks represents the seventh highest of all time. Barty finishes her career with 15 singles titles in total and 12 in doubles, while she ends with a 305-102 win-loss singles record, and 200-64 in doubles.