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.
Rafael Nadal's decision to end his season early means Cilic is actually holding the last berth for the eight-man showdown at London's O2 Arena.
Roger Federer added yet another record to his vast collection when he guaranteed becoming the oldest ATP world number one by beating Dutchman Robin Haase 4-6, 6-1, 6-1 to reach the semi-finals in Rotterdam on Friday.
It is time for the men's and women's professional tennis bodies to merge says former world number one Kim Clijsters.
Japan's Kei Nishikori will make a third straight appearance at the ATP Tour finals next month after becoming the fifth player to qualify for the season-ending tournament, organisers said on Wednesday.
The former world number two, Alexander Zverev has repeatedly rejected the claims by his former girlfriend Brenda Patea that she was a victim of bodily harm during an argument in 2020, his lawyers have said.
Serbian tennis ace Novak Djokovic has continued his domination on an unchanged top 10 in the latest men's tennis rankings issued by the ATP on Monday.
Russian Andrey Rublev beat Norwegian top seed Casper Ruud
The 36-year-old was given a thorough workout by Sock although had he been a little more clinical the scoreline would have been more heavily-weighted in his favour.
Ronaldo got involved in ball kid duties while watching world number one Novak Djokovic's opening match against John Isner of America as the tennis ball bounced into the stands near the first row where he was sitting.
British world number 55 Jack Draper had no time to enjoy sealing what he described as one of the most satisfactory wins of his career at the Australian Open on Tuesday as he was forced to race to a courtside bin to throw up.
A mouthwatering finale to the season ended before it even began on Sunday when Roger Federer was forced to pull out prior to the ATP World Tour Final showdown with Novak Djokovic.
Former Australian player Brad Drewett was named on Thursday as the new head of the men's governing tennis body the ATP.
Three contenders for the men's singles title at the Australian Open, which starts on Sunday.
Britain number one Andy Murray has overtaken 14-time Grand Slam champion Rafael Nadal to claim the third spot in the ATP world rankings.
The opening match in the Pete Sampras Group produced a feast of stylish backhands from both players but it was Dimitrov, the first Bulgarian to qualify for the tournament in its 48-year-old history, who overcome some late jitters to prevail.
Former doubles world No. 1 Leander Paes was recently elected to receive the Ultimate Honour in Tennis - induction into the International Tennis Hall of Fame - as the Class of 2024.
'I've never been of the thought that Rafa needs rhythm because he's too good for that. But now the situation is different.'
Nadal expresses doubt over Australian Open participation
The victory saw him move up by three places to stand only behind Spain's Rafael Nadal and Swiss star Roger Federer.
Bopanna and Ebden won 7-6(0), 7-5 in the final that lasted one hour and 39 minutes.
Riding on his sizzling performance in the Japan Open, Leander Paes is once again knocking the doors of the top-five zone as he gained two spots to be placed sixth in the ATP doubles world rankings, issued on Monday. Paes and Lukas Dlouhy reached the final of the Japan Open last week but lost the summit clash, missing out on the opportunity to pocket back-to-back ATP titles.
Indian Davis Cupper Mahesh Bhupathi and Mark Knowles cruised into the finals of the euro 891,000 ATP Swiss Indoor tournament, defeating Argentine pair Jose Acasuso and Agustin Calleri in straight sets in Basel on Saturday.
The 43-year-old Bopanna and 35-year-old Ebden, who claimed two doubles titles on the ATP Tour earlier this year, will next face the unseeded British pair of Jacob Fearnley and Johannus Monday on Sunday.
Alcaraz will hope to bury memories of an injury-plagued start to last year when he missed the Australian Open
The ATP had fined him US$106,000 for failing to attend an interview. The world no 1 says he has been defamed and wants the fine dropped.
The ATP launched a novel advertising campaign to promote the game at all its tournament sites.
Rohan Bopanna and his Australian partner Matthew Ebden lost to Russian pair of Andrey Rublev and Karen Khachanov.
Novak Djokovic's tremendous run of form since the start of the year means the Serb has already booked his spot at the ATP World Tour finals in London.
Croatia's Ivo Karlovic became the oldest ATP winner since Jimmy Connors in 1989.
Novak Djokovic has formally withdrawn from the draw for the Indian Wells tournament, organisers said on Sunday in an indication that the world number one's application for a COVID-19 vaccine waiver to enter the US might have failed.
Spanish veteran Feliciano Lopez extended his career by at least one more day with an emotional victory at the Mallorca Open.
Britain's Cameron Norrie fought back from a set down to beat world number two Carlos Alcaraz 5-7, 6-4, 7-5 in the Rio Open final on Sunday.
The former Wimbledon champion has decided to take on the tournament director's role at next year's World Indoor tournament.
Roger Federer rediscovered his verve in the nick of time to outclass Austrian Dominic Thiem 6-2, 6-3, on Tuesday, and maintain his hopes of reaching the last four at the ATP Finals.
'The drive that I have is still there. My body has been serving me well, listening to me well. I have a great team of people around me. The motivation, especially for the biggest tournaments in the sport, is still present.'
India's Mahesh Bhupathi on Monday advanced to the second round of the ATP World Tours Finals after he and his partner Max Mirnyi defeated Lukasz Kubot and Oliver Marach in straight sets at London.
Hauling itself up from World Group II should not be a complicated task for India when it takes on an unostentatious Morocco in the home tie, which will be more of a celebration of Rohan Bopanna's Davis Cup career.
Teenager Kei Nishikori became the first Japanese to reach an ATP final at the Delray Beach International.
Frenchman Julien Benneteau caused a stir during an interview on French radio station RMC Sport on Sunday in which he said tournament referees were often kinder to Federer when it came to scheduling his matches.