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).

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.

Cameron Norrie is hoping Russian players will be allowed to return to Wimbledon in 2023, saying he wants "the best players in the world to be playing".

Following the Russian invasion of Ukraine earlier this year, Russian players were banned from participating at SW19.

This meant the likes of Daniil Medvedev and Andrey Rublev were not able to play and compete for the third grand slam of the year, which Novak Djokovic ended up winning for the seventh time.

The tournament was stripped of ranking points as a result of the ban on Russians, a decision that was met with much frustration from players.

Medvedev and Rublev finished a respective seventh and eighth in the year-end ATP rankings, and both took part in the ATP Finals in Turin.

Norrie hopes they are able to return to Wimbledon next year, telling reporters: "For me, I want the best players in the world to be playing.

"I felt last year was tough for those guys, especially for Daniil and for Andrey, who have a chance of winning Wimbledon.

"I know how much those guys sacrificed with their careers and their goals are obviously very high to be winning Slams.

"So I really did feel bad for those guys."

Jannik Sinner and Marin Cilic were the two most notable first-round losers at the Paris Masters, where Taylor Fritz kept his slim ATP Finals hopes alive on Monday.

World number 12 Sinner, the 11th seed in the French capital this week, suffered a straight-sets loss to Marc-Andrea Huesler, as did 15th favourite Cilic against Lorenzo Musetti.

Ninth seed Fritz downed Alejandro Davidovich Fokina 7-5 6-2, with Cameron Norrie and Frances Tiafoe also recording straight-sets victories against Miomir Kecmanovic and Lorenzo Sonego respectively.

Victory for Fritz kept the American in the hunt for qualifying for November's ATP Finals in Turin for the first time, needing to reach the final in Paris to overtake Felix Auger-Aliassime or Andrey Rublev.

"Right now I'm just focused on kind of playing myself into the tournament," said Fritz. "I feel like any time this year that I've won a couple of matches in a tournament, then I've done well.

"So I'll just try to focus on these early rounds. Turin is still in the picture, obviously, but there's not much else I really could have done.

"Felix has played really, really well, so he deserves it, but I am going to try to steal his spot this week for sure."

Home favourite Gilles Simon awaits Fritz in the second round at the ATP 1000 event after defeating Andy Murray 4-6 7-5 6-3.

Alexander Bublik and Mikael Ymer played out another three-set battle, with the former triumphing 6-1 6-7 (2-7) 6-4.

Richard Gasquet, Yoshihito Nishioka, Karen Khachanov, Maxime Cressy, Nikoloz Basilashvili and John Isner were the other first-round winners on the opening day in France.

Stefanos Tsitsipas crashed out of the Vienna Open after losing in a dramatic third-set tie-break against Borna Coric, who claimed his third successive win over the Greek ace.

The second seed was the highest-profile casualty in the Austrian capital on Thursday, as he succumbed to the Croatian once more 4-6 6-4 7-6 (7-4).

Coric rescued six match points before stunning Tsitsipas at the 2020 US Open, while he also triumphed when they collided in the Cincinnati showpiece in August.

The world number 27's chances of completing a hat-trick of victories appeared bleak at a set and break down, but he rallied to force a decider that went the distance, before holding his nerve for another notable win.

Coric's reward is a quarter-final clash with Hubert Hurkacz, who boosted his chances of qualifying for next month's ATP Finals with a 7-5 4-6 6-3 win over Emil Ruusuvuori.

Daniil Medvedev advanced to the last eight after a 6-3 6-3 victory over home favourite Dominic Thiem. Next up for the top seed is Jannik Sinner after the Italian saw off Francisco Cerundolo 7-5 6-3.

Third seed Andrey Rublev's ATP Finals hopes were dented after a 6-3 6-4 defeat by Grigor Dimitrov, who will play Marcos Giron after the American overcame seventh seed Cameron Norrie in straight sets.

Over in Basel, third seed Felix Auger-Aliassime required just 49 minutes to complete a commanding 6-1 6-0 rout of Miomir Kecmanovic for his 10th straight ATP win.

Meanwhile, Stockholm champion Holger Rune continued his momentum by recording a seventh straight victory after seeing off Ugo Humbert 6-4 6-2.

Sixth seed Roberto Bautista Agut enjoyed a straight-sets win over three-time grand slam champion Andy Murray to set up a clash with home favourite Stan Wawrinka, who outlasted Brandon Nakashima in a deciding set.

Stan Wawrinka rolled back the years for a glorious victory over Casper Ruud at the Swiss Indoors, joining fellow veteran Andy Murray in putting on a show in Basel.

Former world number one Murray pulled off a remarkable win over Russian Roman Safiullin, winning five games in a row from 4-1 behind in the final set.

But that was just a tease for the excitement that followed, as Wawrinka, who like Murray won three grand slam titles in his prime, felled second seed Ruud in straight sets.

The 37-year-old Swiss delighted his home crowd with a 6-4 6-4 victory over this season's French Open and US Open runner-up, serving nine aces as he defied a world ranking of 194th to produce some of his old magic.

Murray has fallen away from the elite ,too, but at 49th in the world he is not far away from rejoining that pack, although defeat looked to be beckoning against Safiullin.

The 35-year-old Scot fist-pumped with relief at recovering the break of serve that Safiullin snatched early in the decider, and Murray hit a service winner on his second match point to seal a 6-7 (5-7) 6-3 6-4 success.

The victory for two-time Wimbledon winner Murray took him to 26 wins this season, the most he has had in a single campaign since pulling off an astounding 78 victories in 2016, the year he won at the All England Club for a second time, landed a second Olympic gold medal and finished top of the rankings.

Murray said of his win: "As the match went on, I started to dictate a few more points and served better."

Quoted on the ATP website, he added: "I changed the way I was returning a little bit, and when I did that, I was able to create a few more opportunities and frustrate him a little bit."

Pablo Carreno Busta scored a 6-2 6-1 win against Argentinian Sebastian Baez, with Alex Molcan, Dominic Stricker and Botic van de Zandschulp also advancing to the last-16 stage.

At the Vienna Open, Murray's fellow British players Cameron Norrie and Dan Evans both went through to the second round, Norrie beating Argentina's Pedro Cachin 3-6 6-2 7-6 (7-1) and Evans fending off Germany's Oscar Otte 6-4 7-6 (7-3).

Canadian left-hander Denis Shapovalov beat Austrian wildcard Jurij Rodionov, but the home crowd had something to celebrate when former US Open champion Dominic Thiem continued his resurgence by eking out a 2-6 7-6 (7-2) 7-6 (8-6) victory against American Tommy Paul, saving two match points.

Dominic Thiem saved three match points before beating Hubert Hurkacz for the first time to reach the semi-finals of the European Open on Friday.

Thiem was on the brink of being knocked out by the top seed in Antwerp, but fought back to win 3-6 7-6 (11-9) 7-6 (7-4).

The 2020 US Open champion fended off all three match points in a second-set tie-break to take a thrilling quarter-final the distance and then came out on top in another breaker to advance.

Thiem will do battle with Sebastian Korda for a place in the final after the American emphatically defeated eighth seed Yoshihito Nishioka 6-0 6-2.

Richard Gasquet moved into the last four at the expense of David Goffin and will face Felix Auger-Aliassime, who came from a set down to beat Dan Evans.

Matteo Berrettini remains in the hunt to win the Tennis Napoli Cup on home soil after a 6-2 6-3 quarter-final triumph over Taro Daniel.

Top seed Pablo Carreno Busta crashed out in Italy, losing 7-5 6-2 to Miomir Kecmanovic, who will face Lorenzo Musetti after he got the better of Daniel Elahi Galan. Mackenzie McDonald will come up against Berrettini after getting past Zhang Zhizhen.

Stefanos Tsitsipas sealed a Stockholm Open semi-final spot with a 7-5 6-3 win over Mikael Ymer and will take on Emil Ruusuvuori, who eliminated Frances Tiafoe.

Holger Rune and Alex de Minaur meet in the other last-four match in the Swedish capital following wins over Cameron Norrie and Denis Shapovalov respectively.

Cameron Norrie fought back from a first-set loss against Aslan Karatsev to advance into the quarter-finals of the Stockholm Open, keeping hopes of qualifying for next month's ATP finals alive.

Norrie's return to action, having withdrawn from last month's Korea Open with illness, was not plain sailing as Karatsev won the first set tie-break 10-8 to put the Brit under pressure.

However, the 27-year-old responded by taking the next two sets 6-3 6-4 to seal safe passage, helped by six first-serve aces, which also maintains his hopes of a spot in November's finals and sets up a tie against 19-year-old Holger Rune.

Top seed Stefanos Tsitsipas was given a sterner test by Maxime Cressy before eventually securing a spot in the quarter-finals 7-6 (7-5) 7-6 (14-12) in a two-hour contest, while Denis Shapovalov also beat Antoine Bellier in straight sets.

The number one seed is through at the European Open in Antwerp as well as Hubert Hurkacz toppled Jack Draper 7-6 (7-5) 6-7 (5-7) 6-1.

Britain's Dan Evans eased into the final eight after securing a 6-2 6-1 victory against Constant Lestienne, while there were also victories for Yoshihito Nishioka and Richard Gasquet.

Elsewhere, sixth-seed Sebastian Baez was a 7-5 7-6 (7-3) winner against Lorenzo Sonego in the Napoli Open, where Roberto Carballes Baena and Corentin Moutet were among the other victors.

Casper Ruud saw off a fightback from Nicolas Jarry to book his spot in the quarter-finals of the Korea Open, as well as this year's ATP Finals.

The top seed was given a second set scare by the Chilean but wrestled back control to emerge as the victor in a 6-2 3-6 6-3 encounter.

The two-time grand slam finalist, having been runner-up at Wimbledon and the US Open this year, will face Yoshihito Nishioka after he saw off Japanese compatriot Taro Daniel in a 6-2 6-4 win.

His victory also ensured his place at the ATP Tour's end-of-year finale in Turin, alongside Spanish duo Rafael Nadal and Carlos Alcaraz.

Cameron Norrie remains on course to set up a potential final in Korea with Ruud after brushing aside Kaichi Uchida with a comfortable 6-2 6-2 victory.

The Briton will face eighth seed Jenson Brooksby after he turned over home favourite Kwon Soon-woo in a 6-3 6-4 result in Seoul.

Brooksby's fellow Americans Mackenzie McDonald and Aleksandar Kovacevic also came through their last-16 encounters to set up a quarter-final clash against each other.

Novak Djokovic played a vital role in Team Europe opening up a four-point lead in the Laver Cup as he won in singles and doubles upon his return to the ATP Tour after a three-month absence.

Djokovic had not played since taking his grand slam count to 21 with the Wimbledon title in July, but he looked as if he had hardly been away as the Serbian beat Frances Tiafoe and then teamed up with Matteo Berrettini in the doubles.

Tiafoe beat Rafael Nadal at the US Open earlier this month and combined with Jack Sock on Friday to defeat the Spaniard again in what was Roger Federer's last ever match, but the American could not get to grips with Djokovic in Saturday's final singles contest.

Djokovic's 6-1 6-3 win secured two points for Team Europe to put them out in front, and he was involved again in the last of the day's action as the team's advantage doubled to four points.

Berrettini and Djokovic tussled with Sock and Alex de Minaur and ultimately had too much, winning 7-5 6-2 in less than an hour and a half.

Earlier, Taylor Fritz's three-set triumph over Cameron Norrie put Team World briefly back on level terms.

Fritz made a brutal start but ended up being forced to a match tie-break, eventually coming through with a 6-1 4-6 10-8 victory.

That wiped out the two-point lead Berrettini had given Europe in the first match of the day, with the Italian edging Saturday's most gruelling tussle.

He saw off Felix Auger-Aliassime 7-6 (13-11) 4-6 10-7, and despite finding himself on court for over two hours, Berrettini was still sharp enough to emerge victorious alongside Djokovic.

Rafael Nadal has withdrawn from the Laver Cup after being paired with Roger Federer for the final match of the Swiss star's career on Friday.

Federer had announced he would be retiring following the tournament and was then only fit to feature in one doubles match.

But that gave the Swiss great the opportunity to team up with Nadal, with the duo falling to a narrow and entertaining 4-6 7-6 (7-2) 11-9 loss to Jack Sock and Frances Tiafoe at the O2 Arena.

That defeat marked the end of Federer's involvement in the Laver Cup, and Nadal's participation is over for this year, too.

Nadal has been dealing with an abdominal injury in the second half of this season, with the issue notably seeing him miss a Wimbledon semi-final against Nick Kyrgios.

However, the Laver Cup, announcing the Spaniard's absence from the weekend's play on Saturday, made no reference to any ailment, saying he had pulled out "for personal reasons".

Cameron Norrie took Nadal's place in the tournament and was set to face Taylor Fritz.