Djokovic into quarter-finals

Novak Djokovic moved into the quarter-finals of a grand slam for the 22nd time in a row after beating Philipp Kohlschreiber in their last 16 clash at the US Open.

Kohlschreiber, the 22nd seed, was the last man to deny Djokovic a place in the last eight of a major tournament, beating him in the third round at Roland Garros in 2009, but had no answer against the World No 1 this time.

Top seed Djokovic made a lightning start, winning the first four games, and although Kohlschreiber began to find some rhythm he could do nothing to prevent a 6-1 7-5 6-4 victory for the Serb.

Djokovic broke Kohlschreiber twice as he steamrollered his way through the opening set in 25 minutes.

The second set was a much closer affair, and Djokovic was serving to stay alive as he trailed 4-5, 30-40, but a cross-court forehand denied Kohlschreiber and, buoyed, he swiftly broke his opponent to go two sets up.

Another unforced error from Kohlschreiber put him in an early hole in the third set, and there was no way back from there.

"It was very humid for both of us," Djokovic said on the tournament website. "We had a lot of long rallies. The match could have gone either way, especially in the second set."

Third seed Stan Wawrinka reached the quarter-finals with a 7-5 4-6 7-6 (9/7) 6-2 victory over Spain's Tommy Robredo.

It is the fourth time in his last five grand slams that the Australian Open champion has made the last eight, but he did it the hard way.

After receiving treatment in the third set when he ended up in the stands after trying to chase down a backhand, the Swiss had to save two set points in the tie-break.

He and Robredo had words in the fourth set but by that point Wawrinka, who beat Murray in the quarters last year, was already firmly in control.

"Mentally I was really strong today," said Wawrinka. "I was accepting the fact that I was really down physically in the third set, that I was struggling a lot with cramping and everything. But I wasn't complaining about that. "I stayed positive with that, tried to find the solution how to relax mentally, how to be better, how to fight with him."