Even if Federer loses in straight sets, he can still make it to the semis if he wins at least 5 games if both sets go to 6.
The Austrian world No. 8 - already beaten by Kevin Anderson and Roger Federer in his first two round-robin matches - flew out of the blocks at London's 02 Arena, breaking twice to take the first set.
Second seed Federer suffered a painful loss at the hands of Anderson in the Wimbledon quarter-finals this year after leading by two sets, his only defeat against him in five meetings before Thursday's clash.
Benneteau said that tournament referees were often nicer to Federer when it came to the schedule of his matches in an interview with French radio station RMC Sport.
"I am not the youngest but I am enjoying myself and I just want to play one more good match".
But Anderson, who has become the first South African to reach the semis of this event, broke back immediately as Federer's usually dependable serve went amiss. "Well, you never know what happens tonight, but I don't think it's going to happen".
John Isner also voiced his opinion on the subject: "I think those guys are the ones that, by and large, carry our sport in a big way and they deserve everything they've ever earned". "I am very happy that I won a Grand Slam".
"I understand Julien's point because sometimes it does seem that maybe certain players get more favored year after year in certain tournaments", said Djokovic.
'I felt fresh, but I just didn't feel the ball this week, ' said Nishikori.
Swiss tennis maestro Roger Federer stormed into the semi-final of the ongoing ATP Finals tournament after defeating Kevin Anderson of South Africa in the men's singles event here on Friday. The following game was also very long and Thiem converted the fifth break point after a double fault from Nishikori, closing the set with a forehand victor in the following game after 41 minutes.
"I don't really in feel the mood during a World Tour Finals to discuss that topic, to be honest", he said.
"From that standpoint, it was more straightforward for me today".
"I'm happy to be alive, hoping for a good match the day after tomorrow".
However, Federer steadied himself and made a delicate drop volley to break once more in the following game, before eventually closing out the set to maintain his record of having only missed the semifinals once in 16 appearances at the tournament.