World number one Iga Swiatek had no problem dealing with Camila Osorio during Wednesday's second round, advancing with a 6-2 6-3 victory.

Swiatek, 21, is seeking her fourth grand slam title and her first at the Australian Open, having already won the French Open twice before claiming her first US Open crown this past season.

Against Osorio, it was Swiatek's ability to consistently return that was the difference, holding the Colombian to just a 31 per cent success rate on her service points in the opening set (eight-of-26).

It resulted in a lightning-quick start for the Polish superstar, winning the first four games of the match, and despite giving back a couple breaks of serve, Swiatek did not allow Osorio to hold serve a single time in the opening frame.

Osorio was able to finally hold serve to begin the second set, before Swiatek again rattled off four consecutive games to collect a double-break and a winning lead.

In a remarkably clean performance from the tournament favourite, Swiatek landed 80 per cent of her first serves fair while committing no double faults, and both players finished with more winners than unforced errors.

With the victory, Swiatek will now face the winner between Cristina Bucsa and Bianca Andreescu in the third round.

Data Slam: Swiatek in legendary company

Swiatek has now won 53 of her first 65 grand slam matches – the sixth-best total through 65 attempts in the Open Era.

She trails only Margaret Court (61), Monica Seles (60), Chris Evert (57), Martina Hingis (56), Billie Jean King (56) and Tracy Austin (54).

WINNERS/UNFORCED ERRORS

Swiatek – 19/16

Osorio – 16/14

ACES/DOUBLE FAULTS

Swiatek – 0/0

Osorio – 0/2

BREAK POINTS WON

Swiatek – 6/8

Osorio – 3/5

Iga Swiatek believes people sometimes treat her like a "robot who has to win all the time" and are focused too much on "numbers and statistics."

Swiatek came through her first-round match at the Australian Open on Monday as she beat Jule Niemeier 6-4 7-5, though she trailed 5-3 in the second set before winning four-straight games.

The world number one will face Camila Osorio in the second round on Wednesday, and admitted she had needed to find another gear to overcome her German opponent.

"I knew that I could get my focus up a little bit, [increase] the intensity a little bit more. So I did that," she said.

"But my goal for my next matches is not being in those situations and not starting the set with losing a break, but it happens. I'm happy that I was able to come back. It wasn't like I needed to really change a lot. I just needed to have more intensity."

After an impressive 2022 season, that saw her win the French Open and US Open, expectations have risen around Swiatek, which the 21-year-old has noticed.

"For sure, I feel like people are really focused on the numbers and on the statistics," she said. "I feel like they're looking at those matches not seeing that we are still people, and we have to really fight for it. 

"I know that I also put a lot of expectations on myself, but I'm working on that. It just feels like sometimes they're not treating you still as a human, but more like a robot who has to win."

Swiatek has now won the first round in a grand slam tournament in 15 of her previous 16 appearances, but admitted she only developed confidence in playing on hard courts last year.

"At the beginning of last year I didn't have that much confidence that I can also win big titles on hard court because all of them basically happened last season," she said.

"Also before I think the media kind of described me as a clay court player. Maybe that got into me a little bit. But, yeah, for sure working with [coach] Tomasz [Wiktorowski], I just felt like I can be more aggressive on hard court. I don't have to be the baseline player. I really used that in my matches, then the results kind of showed me that I'm going right direction."

Iga Swiatek made it through to the second round of the Australian Open with a 6-4 7-5 win against Jule Niemeier, though was again tested by the German.

In a rematch of their US Open fourth-round match in which Swiatek had to recover from a set down before going on to ultimately win the tournament, Niemeier gave Swiatek problems again with her power and ability to utilise the fast conditions.

An even first set saw Swiatek unable to find a break point until she was 5-4 ahead, before forcing two set points, eventually taking the second as a strong forehand could only be returned into the net.

Niemeier came out in the second set determined to make amends, though, breaking Swiatek in the opening game as she looked to overwhelm the Pole.

The 23-year-old belied her status as the world number 69, causing the top seed problems as she mixed power hitting with some nice drop shots but, as she served for the set, Swiatek turned up the dial and forced the break to level at 5-5.

After holding her own serve it looked like the second set would head to a tie-break, but Swiatek's increase in intensity made the difference again as some expertly placed deep and wide shots caused another break as she sealed a straight-sets win.

"Honestly I wanted to be focused on myself because she can serve amazing," Swiatek said in her on-court interview. "She uses fast conditions so I just wanted to think what I could do to push her back.

"I'm pretty happy I got through this match because the fist round is always tricky and playing Jule is always tricky."

Data slam: Swiatek takes advantage of second serve

Niemeier's serve gave Swiatek problems throughout, but the Pole was ruthless when she was given rare opportunities.

Despite a success on her first serve of 71 per cent (32/45), Niemeier could only win 35 per cent on her second (9/26).

WINNERS/UNFORCED ERRORS

Swiatek – 20/28

Niemeier – 18/29

ACES/DOUBLE FAULTS

Swiatek – 0/3

Niemeier – 3/1

BREAK POINTS WON

Swiatek – 3/5

Niemeier – 1/3

Iga Swiatek had a reminder of the stellar rivalry that never was when she practised alongside Ash Barty on Saturday ahead of the Australian Open.

Australian Barty is the reigning women's singles champion at Melbourne Park, but she retired just weeks after lifting the trophy last year.

That shock decision from the then 25-year-old saw a figurehead of the WTA Tour make way, and Swiatek has taken her place as the undisputed world number one, saying Barty has inspired her to hit those heights.

The prospect of Barty and an ever-improving Swiatek fighting for the tour's biggest titles was dashed, and they only ever played twice, with Barty winning both times.

Barty announced on January 6 she is pregnant, and she appears to have no inclination to perform a retirement U-turn.

"For sure, when she retired, I felt like she still had the best tennis out there," Swiatek said after their light-hearted court session.

"So, I was pretty sad that I'm not going to be able to compete against her and maybe win.

"But on the other hand, she gave me a lot in terms of my motivation and my kind of willingness to practise even more and to have more variety on court.

"When I played against her, I felt like she just has all these different game styles and slice. Even in her book, she says she has five types of slice. I don't know how that's possible. I still haven't figured out only one type.

"I have huge respect for Ash. She really gave me huge motivation at the beginning of last season to get even better. I'm kind of grateful for that."

Swiatek will play the first night session match on Rod Laver Arena at this year's championships, taking on a familiar foe in Germany's Jule Niemeier.

At the US Open last September, the heavy-hitting Niemeier led by a set and a break against Swiatek in the fourth round, only to let the Pole back in and eventually surrender the third set 6-0. Swiatek went on to win the title, her third grand slam trophy success.

Niemeier also reached the Wimbledon quarter-finals, and Swiatek is wary of the opening test that awaits.

"We played at the US Open, and you saw how intense that match was, how tough," Swiatek said. "It's not going to be easy.

"But on the other hand, any match in a grand slam is always more intense and more stressful than other tournaments. I'll be ready for it.

"It's nice also that we played not so long ago, so I can take a lot from that match. Now I know how her ball feels on the racket. So, we'll see. But she has the same."

Iga Swiatek starts the Australian Open as almost as strong a favourite to win the women's singles as Novak Djokovic is for the men's event.

Considering Djokovic is a nine-time champion in Melbourne, and Swiatek has never reached the final, that is some going and indicative of the Polish player's dominance on the WTA Tour over the last 11 months.

Swiatek ended last year with eight titles to her name, winning the French Open and US Open among them, and the 21-year-old has accrued more than twice as many ranking points as the next player on the WTA list, Ons Jabeur.

Her ascent to become the dominant woman in tennis has been remarkable, and Swiatek has also earned admiration for her efforts to raise funds for children in war-hit Ukraine.

But is she such an outstanding favourite for the Melbourne Park title as the odds-makers have it?

Since the US Open, she has been a champion at just one – modest by her standards – of the four tournaments she has contested, including the United Cup team event.

Here, Stats Perform looks at five others who might have a say in the destination of the year's first major.

Jessica Pegula

Swiatek was reduced to tears after a 6-2 6-2 drubbing by Pegula on January 6 at the United Cup, her first loss of the year.

She later described Pegula's performance as "the perfect match", and will hope the American cannot always rise to that level.

"It's always hard when you lose, especially when you're playing for the team and your country," Swiatek said at the time, explaining her post-match tears.

Swiatek had won all four of the matches they contested in 2022, dropping only one set, with quarter-final wins on the way to her two grand slam triumphs included in that set.

The result in Sydney, therefore, might have been just a blip, but Pegula is number three in the world for a reason, and Swiatek will surely want to avoid her over the coming fortnight.

Coco Gauff

Is now Gauff's time? There's a question that has been buzzing around the tennis circuit for at least a couple of seasons, despite the American being just 18 years old.

Time, it should be clear, is firmly on her side. She soared to fourth in the rankings in October but has slipped a little since, while remaining firmly established in the top 10.

Given her great talent, Gauff should be resident in the top 10 for many years to come, so we can afford to wait before watching her fly. The sometimes-erratic forehand remains in need of fine-tuning, and Gauff began this year with just two career singles titles to her name after missing out on a trophy in the 2022 season.

However, she reached a first grand slam final last June, losing to Swiatek in Paris, and began 2023 by capturing a title in Auckland where, as top seed, she made light work of the field.

The victory made her the sixth American player to secure three or more WTA-level titles before turning 19 in the last 40 years, after slam winners Monica Seles, Jennifer Capriati, Lindsay Davenport, Venus and Serena Williams.

That is some company for Gauff, who will face Katerina Siniakova in the first rout in Melbourne, to be keeping, and her time will come. It might even come in Melbourne.

Ons Jabeur

After finishing runner-up to Elena Rybakina at Wimbledon and Swiatek at the US Open, Jabeur is targeting a third successive slam final.

The Tunisian would win most popularity contests on the Tour, but she wants one of the big trophies now, and has to be seen as a strong contender in Australia.

Her preparations took a knock with a loss to 18-year-old Czech Linda Noskova at Adelaide International 1, but that will only have made Jabeur work harder in the build-up to the major.

She was gutted to have to pull out of the Australian Open with a back injury last year, and a first-round loss at the French Open followed, but Jabeur came good at the next two majors, albeit falling at the final hurdle.

Aryna Sabalenka

At this time last year, Sabalenka was in crisis, her serve a massive weakness as she struggled to deliver the ball safely.

She recovered from going a set down in three consecutive matches at the Australian Open before losing a rollicking tussle in round four with Estonian veteran and upset specialist Kaia Kanepi.

Sabalenka served a wretched 15 double faults in that match, which was sadly more or less par for her in the early stages of the 2022 season, but the Belarusian got her act together, overcome those yips, and finished the year strongly.

A semi-final run at the US Open was followed by an appearance in the WTA Finals title match, where she lost a close encounter with Caroline Garcia.

Sabalenka began this year not with the serving jitters, but with the Adelaide International 1 title, not dropping a set all week.

She has a big game and with it growing confidence. At the age of 24, she should be entering her prime years, and 2023 could be a special 12 months for the woman with the tiger tattoo.

Zheng Qinwen

The WTA's 2022 Newcomer of the Year winner, Zheng is a 20-year-old Chinese player who could soon follow in the footsteps of compatriot Li Na and begin scooping the biggest prizes in tennis.

How soon? Well, probably not quite yet, but then again very few picked out the then 54th-ranked Swiatek to win the 2020 French Open, the moment that launched her to stardom.

Zheng has rocketed to 30th in the rankings, having begun last year at 126th on the WTA list, and should be considered capable of halving her ranking over this season.

She first came to major prominence at the French Open, when she defeated Simona Halep and for a while also had Swiatek's number in their fourth-round match, winning the first set before menstrual cramps and a leg problem caused her to lose momentum.

The WTA Tour is a learning curve and slam-level success might not come immediately for Zheng, but that newcomer award came her way because she is a player shaping up to have a big say in the sport's future. Along with the likes of Gauff and Swiatek, she could still be a big factor in a decade's time.

Iga Swiatek has no interest in what people expect from her and the world number one will not be "living in the past" as she targets more success this season.

Swiatek was in a class of her own last year, winning a staggering eight titles to firmly establish herself as the best player in the world.

A second French Open title and a maiden US Open triumph were the highlights for the 21-year-old in a stellar 2022.

The Pole will start her quest to win the Australian Open with a first-round match against Germany's Jule Niemeier at Rod Laver Arena on Monday.

Swiatek is the favourite to be crowned champion at Melbourne Park, but will not be putting too much pressure on herself.

"When I don't care about what people think and what their expectations of me are, it's easier for me to succeed," Swiatek told BBC Sport.

"That was what I tried my best to do in 2022.

"Although I'm proud of them, I'm not going to try to match my previous achievements because it would not be constructive.

"A season like that is something amazing and rare. Sure, I would love to do it again, but it's not advantageous to live in the past."

Swiatek was beaten by Danielle Collins at the semi-final stage of the Australian Open 12 months ago.

Nine-time champion Novak Djokovic will make his return to the Australian Open against Spain's world number 75 Roberto Carballes Baena.

After being deported from Australia last year amid a row over his refusal of a COVID-19 vaccination, Djokovic is firmly back in favour and chasing history in Melbourne, with a record-equalling 22nd men's singles grand slam in his sights.

He begins against an opponent who in four previous main draw appearances has only ever won one singles match at Melbourne Park.

Defending champion Rafael Nadal, whose 22 slam titles Djokovic is seeking to match, has a tricky opener against rising British star Jack Draper, the world number 40.

Second seed Casper Ruud will tackle Czech Tomas Machac first up, with the 115th-ranked player unlikely to prove too daunting an obstacle for last season's French Open and US Open runner-up.

Fifth seed Andrey Rublev could face an awkward assignment against wildcard and former US Open winner Dominic Thiem, while Australia's Nick Kyrgios begins against Russian Roman Safiullin.

Neither 13th seed Matteo Berrettini nor five-time runner-up Andy Murray would have been delighted to be paired together, but that is what happened in Thursday's draw.

In the women's singles, top seed Iga Swiatek starts her bid for a first Australian Open title against Germany's Jule Niemeier, who caught the eye last year on a run to the Wimbledon quarter-finals.

American seventh seed Coco Gauff starts against Czech Katerina Siniakova, while Jessica Pegula, Gauff's third-seeded compatriot who recently beat Swiatek in the United Cup, will face Belgian Jaqueline Cristian.

Gauff could face former US Open winner Emma Raducanu in the second round. Unseeded Briton Raducanu starts against Germany's Tamara Korpatsch.

Former champions Sofia Kenin and Victoria Azarenka go head to head in the first round, with American Kenin unseeded this year and Belarusian Azarenka the 24th seed.

Azarenka's compatriot Aryna Sabalenka is fancied to do well, having banished last year's serving yips, and the fifth seed starts against Czech Tereza Martincova.

Tunisian second seed Ons Jabeur, runner-up at Wimbledon and the US Open, begins her latest quest for an elusive grand slam title against Slovenian world number 88 Tamara Zidansek.

Former US Open winner Bianca Andreescu is unseeded in Australia and Czech 25th seed Marie Bouzkova drew a possible short straw by getting the Canadian in round one.

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.

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.

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.

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."

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.