Federer doesn't much like Djokovic's tone

Both players lost their Finals group stage opener - Nishikori to Novak Djokovic and Berdych to Roger Federer, meaning a second defeat for either player would leave their semi-finals hopes hanging by a thread.

Nishikori shook off the drubbing by Djokovic to beat Berdych 7-5, 3-6, 6-3. A few scrappy play from Berdych left the Czech player down at 0-40 and Nishikori broke his opponent from there to serve for the match. Nishikori, then, produced a near ideal service game to win the set and game.

Asia's top player said he was looking forward to Thursday's clash with Federer, the youngest player in the tournament facing the oldest.

He faced a break point immediately but a good serve helped him save it, and that seemed to settle him into the match. If Nishikori has beaten Federer, Berdych can keep Djokovic out of the semifinals with a win over the Serb; if Federer beats Nishikori, Berdych will need to win in straight sets (so Djokovic can guarantee his spot by winning one set). "Roger is a great guy and it is pleasure for me to be around him".

That would change dramatically with the score at 6-5 to Federer, with the Swiss superstar managing to amazingly break the World No. 1 and move ahead in the contest.

The Japanese world number eight clinched the first set on serve with a pinpoint forehand victor past the wrong-footed Czech world number six. Federer had a first set point at 30-40 up, but hit the net in a rally.

For the second time in his career, Djokovic would win his third major of the year at the US Open, this one at the expense of Federer under the lights in Arthur Ashe Stadium 6-4, 5-7, 6-4, 6-4. "Don't know if it made me play better, but it was a solid match and I'm very pleased where my game's at right now".

In the first set, Federer converted his second set point with a delicate backhand drop over the net that had the six-time champion's numerous fans on their feet celebrating. The game witnessed Djokovic " s super coach Boris Becker missing from his box for a prolong time and his player talking to himself in an annoying fashion. Federer produced a superior service game to consolidate the break to 5-2 in the second set.

Federer had said in the build-up he did not feel far away from Djokovic's level despite the Serbian's dominance and the huge gap in ranking points.

Djokovic had won 16 straight matches at the ATP World Tour Finals, including wins over Federer in 2012, 2013 and 2014.

Kei Nishikori won it, and the match. Djokovic 2015 form is imperious, though.

The usually immaculate Federer may have forgotten to shave, but the 17-time grand slam champion showed he still remembers how to win against the man he had lost to in four of their five previous encounters, including this year's Wimbledon and US Open finals.