Three-time champion Novak Djokovic battled past Frenchman Corentin Moutet in a match that lasted more than three hours on Thursday.
18-year-old Carlos Alcaraz of Spain became the youngest to clinch an ATP 500 title at the same event on Sunday when he defeated Diego Schwartzman in the final of the Rio Open.
Roger Federer's proposal to merge the tours gets thumbs up from top players.
Team Europe and Team World are tied at 2 after one day of the Laver Cup after play opened Friday in Berlin.
The 32-year-old debutant at the ATP's blue riband event won the first 11 games of the round-robin clash before a relieved Nishikori finally got on the scoreboard with an angled winner.
Dimitrov was showing signs of fatigue from his three-hour third-round match earlier in the week and could do little to stop the Spanish world number three, who next faces Argentine Francisco Cerundolo.
The All India Tennis Association (AITA) selection panel picked a five-member squad in which Mukund will be the highest-ranked singles player at number 368.
'I've never been a fan of division in our sport, but I've always fought for better representation and influence of and positioning of the players globally in our sport, which I think is still not where I think it should be.'
World No 1 Novak Djokovic was beaten by Tomas Machac in the Geneva Open semi-finals.
Daniil Medvedev destroyed his racket and a net camera in a mid-match meltdown as he survived a huge scare against Thai wildcard Kasidit Samrej.
World number six James Blake called on the ATP Tour to change the rules at round-robin tournaments after a bizarre 24 hours when he went out of the Las Vegas Open, was reinstated and then eliminated again.
Playing in his first competitive singles match on the ATP Tour since August 5, the 20-times Grand Slam champion showed no signs of rust in his second round win against Lithuanian qualifier Ricardas Berankis.
The Indians will now lock horns with top seeds Ivan Dodig of Croatia and Brazilian Marcelo Melo in the summit clash of the of the ATP 250 event.
Alexander Zverev cruised past Frenchman Lucas Pouille in straight sets in the first round of the Australian Open on Sunday.
Former world number one Andy Murray is in line to play Grigor Dimitrov in the opening round of the inaugural ATP Cup, with Bulgaria qualifying among the final six teams in the nation-based tournament.
Novak Djokovic missed two of this year's four Grand Slams due to not being vaccinated against the novel coronavirus but the Serbian said he has no regrets about his decision.
Factbox on Italy's Jannik Sinner, who beat Germany's Alexander Zverev 6-3, 7-6(4), 6-3 in the Australian Open final
Carlos Alcaraz beat lucky loser Jan-Lennard Struff in the Madrid Open final on Sunday to defend last year's title and win his fourth ATP Tour trophy of the year
Roger Federer said he is "definitely" intending to return to top-level tennis in 2023, but added that he had not made any concrete plans beyond his scheduled appearances at the Laver Cup and his home tournament in Basel later this year.
The events will be on single-year licence as the ATP offers professionals the opportunity to earn money and ranking points in the wake of the coronavirus shutdown.
India's Yuki Bhambri and his French partner Albano Olivetti frittered away a solid start to make a semi-final exit from the ASB Classic in Auckland.
The Indo-Pakistan tennis duo of Rohan Bopanna and Aisam-ul-Haq Qureshi has booked a berth in the season-ending ATP World Tour Finals to be held from November 20 to 27 at London's O2 arena.
For the second consecutive Davis Cup tie, India are relying on doubles specialist N Sriram Balaji to do the singles duty
The decision to lift the ban was met with protest from Ukraine, whose Foreign Minister Dmytro Kuleba said it was "immoral" and urged Britain to deny Russian and Belarusian players visas.
Third seed Alexander Zverev eased past home favourite Ugo Humbert
The Spaniard bore little resemblance to the player who once terrorised his opponents as he slumped to a 6-1, 7-6 defeat by Russia's Nikolay Davydenko.
Medvedev became only the fourth player in ATP history to beat the world's top three at the same tournament.
The former world number one, who is easing his way back to full match fitness after a career-saving resurfacing procedure in January, saved all four break points he faced and dropped only six points on his first serve.
Unseeded Alejandro Tabilo beat twice champion Novak Djokovic 6-3, 6-4 in the second round of the Monte Carlo Masters on Wednesday to maintain a remarkable 100 percent record win record over the 24-times major winner.
Having dug in early on to stay with Federer, Nishikori ended up running away with the match to inflict a first straight sets defeat in the ATP Finals round-robin stages on the 20-time Grand Slam champion.
ATP Tour remembered Maradona with a social media post saying "A champion and icon loved by all", accompanied with a picture of Maradona with Federer.
Zverev has consistently denied all the allegations.
Rohan Bopanna and his partner Matwe Middelkoop beat Santiago Gonzalez and Andres Molteni in the summit clash to claim the doubles title at the ATP tennis tournament in Tel Aviv on Sunday.
The last time the Swiss maestro was this far down in the ATP rankings was all the way back on January 2001, when Federer was just 19 years old. Notably, he was yet to win his first tour title.
Lopez was cheered on by 22-time Grand Slam champion Nadal during his final event as a professional.
As the spotlight shines on Carlos Alcaraz's title defence and Novak Djokovic's pursuit of a record 25th Grand Slam, a determined group of challengers is quietly preparing to shake up the draw.
Bulgaria's Grigor Dimitrov won his first ATP tour title by fighting back to upset Spanish top seed David Ferrer 2-6, 6-3, 6-4 in the final of the Stockholm Open on Sunday.
'It was very evident when we watched you play and the aura you brought on court is unmatchable.' 'And for me, you're always going to be the greatest of all time.'
Russian Andrey Rublev has become the fifth singles player to qualify for the season-ending ATP Finals in Turin next month, the men's tour said.
Factbox on Austria's Dominic Thiem, who beat German Alexander Zverev 2-6, 4-6, 6-4, 6-3, 7-6(6) to win the US Open title on Sunday.
