Novak Djokovic, Andy Murray Book US Open Quarter-Final Showdown

Former champions Novak Djokovic and Andy Murray booked a tantalizing US Open quarter-final duel on Monday with straight-sets fourth-round victories. (Also Read: Serena Storms Into Quarters)

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."

Andy Murray in action during US Open 2014.

© AP

- 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."

Two of the ATP's rising stars will duel under the floodlights as 23-year-old Canadian Milos Raonic and 24-year-old Kei Nishikori of Japan reprise their fourth-round clash at Wimbledon -- won by Raonic on his way to a first Grand Slam semi-final.

The fifth-seeded Raonic is enjoying a career-best season, and at a career-best number six in the world is the second-youngest player, behind 23-year-old Grigor Dimitrov, in the top 10.

Nishikori, the 10th seed, became the first Japanese man to break into the top 10 this season with two titles.

While Raonic has the reputation of a big-server -- with the second-most aces this year on the ATP tour, Nishikori has been impressive on his serve in reaching the last 16. He's been broken only twice, saving 17 of 19 break points he faced in his first three matches.

The winner will face Wawrinka for a semi-final place.