US Open: Djokovic, Murray book quarter-final showdown

New York: Former champions Novak Djokovic and Andy Murray booked a tantalizing US Open quarter-final duel on Monday with straight-sets fourth-round victories.

World number one and top seed Djokovic didn't let Philipp Kohlschreiber stand in the way of another Grand Slam last-eight appearance, defeating the 22nd seed from Germany 6-1, 7-5, 6-4 on another oppressively muggy New York day.

Eighth-seeded Scot Murray advanced with a hard-fought 7-5, 7-5, 6-4 victory over ninth-seeded Jo-Wilfried Tsonga, avenging a loss to the Frenchman in the Toronto Masters last month.

Djokovic and Murray boast a long rivalry in which the Serbian owns a 12-8 record.

They are 2-2 in Grand Slam finals, including Murray's triumph over Djokovic in the 2012 final at Flushing Meadows for his first major crown.

"Tough match," Murray said of the looming contest. "We've had a lot of long ones. We played a long one here a few years ago -- I have great memories from that match."

Djokovic reached his 22nd straight Grand Slam quarter-final, a run that stretches back to Kohlschreiber's victory over him in the third round of the 2009 French Open.

"I'm very glad obviously that I had so many consecutive quarter-finals of Grand Slams. It says that I do value these tournaments the most and try to always perform my best tennis in them," Djokovic said.

The Wimbledon champion looked headed for a short day's work when he raced through the first set in 25 minutes.

But Kohlschreiber dug in, keeping his nose in front on serve and forcing Djokovic to fend off a set point in the 10th game of the second.

Djokovic did so with a stinging forehand passing shot to end a rally that sent the Louis Armstrong Stadium crowd wild, then broke Kohlschreiber for a 6-5 lead.

Serving for the set Djokovic saved another break point with an off-speed service winner and having wrapped up the second set he broke Kohlschreiber to open the third and marched home from there.

"It doesn't feel that it went very easily," Djokovic said. "Philipp is a tough player."

Tough conditions:

Murray broke Tsonga in the final game of each set en route to his victory, first recovering an early break in both the second and third.

"It was extremely tough conditions, very humid and obviously windy," Murray said. "It started to cool down at the end, but the first two sets were very long tough sets."

Australian Open champion Stan Wawrinka, the third seed, powered past 16th-seeded Spaniard Tommy Robredo 7-5, 4-6, 7-6 (9/7), 6-2.

Wawrinka fired 18 aces and 75 winners -- to Robredo's 19 -- saving two set points in the third-set tiebreaker and dominating the fourth set.

"It was a really tough battle today," said Wawrinka, who also survived a tumble into the courtside seats in Armstrong Stadium when he hit the board surrounding the court at full stretch for a shot.

"From that I'm OK, I'm more tired from the running, from the match," he said. "When you win, it's always more easy to feel good after."

Nishikori beats Raonic in record-tying late finish:

Japan's Kei Nishikori booked a US Open quarter-final berth on Tuesday morning with a five-set victory over Milos Raonic that equalled the latest-finishing contests in tournament history.

Nishikori, the 10th seed, defeated the fifth-seeded Canadian 4-6, 7-6 (7/4), 6-7 (6/8), 7-5, 6-4 and will face Australian Open champion Stan Wawrinka for a place in the semi-finals.

The 2:26 am (0626 GMT) finish equalled the record for the latest at the US Open shared by two prior contests: Philipp Kohlschreiber's 6-4, 3-6, 4-6, 6-3, 6-4 third-round win over John Isner on September 3, 2012 and Mats Wilander's 7-6 (7/3), 3-6, 1-6, 7-6 (8/6), 6-4 win over Swedish compatriot Mikael Pernfors in a second round match in 1993.