Andy Murray, Lleyton Hewitt turn up heat as US Open sweats

Defending champion Andy Murray and 2001 winner Lleyton Hewitt made light of the heavy, humid New York conditions on Sunday to breeze into the US Open last 16.

Third-seeded Murray, who ended his country's 76-year wait for a Grand Slam men's champion when he won his maiden major title in New York last year, eased past Germany's world number 49 Florian Mayer, 7-6 (7/2), 6-2, 6-2.

His win was built on an impressive 42 winners and seven aces.

"I think I need to start my matches quicker than I have been doing. I am not that fast out of the blocks," said the 26-year-old. "But once I got going I was striking the ball cleanly."

Murray, the reigning Olympic and Wimbledon champion, will next face Uzbekistan's world number 65 Denis Istomin, who put out Italian 20th seed Andreas Seppi, 6-3, 6-4, 2-6, 3-6, 6-1.

Istomin will be playing in the last 16 in New York for the first time after ending Seppi's perfect streak of seven five-set wins in 2013. Two of those came against him at the Australian Open and Wimbledon.

Murray defeated Istomin in their only match in the quarter-finals at Brisbane in January this year.

Meanwhile, Hewitt reached the fourth round of a Grand Slam for the 30th time with a 6-3, 7-6 (7/5), 6-1 win over Russia's Evgeny Donskoy.

The former world number one and 2001 champion, who knocked out sixth seed and 2009 winner Juan Martin Del Potro in the second round, last reached the fourth round in New York in 2006, when he went on to the quarter-finals.

"It's always great to come back to New York where it all started for me -- I won the doubles in 2000 and singles in 2001. I have played some of my best tennis here," said Hewitt, who claimed victory on a third match point.

"I think the crowd supports me because my personality is the joy of coming out to play. I feel pretty good. I have had three tough matches where I have had to keep bouncing back all the time."

The 32-year-old world number 66 will face either German 12th seed Tommy Haas or Russia's 21st seed Mikhail Youzhny for a place in the quarter-finals.

Hewitt has a 6-4 winning record over Haas, although their last meeting was back in 2004, and a 5-1 lead over Youzhny.

Fifth seed Tomas Berdych of the Czech Republic and Swiss ninth seed Stanislas Wawrinka will clash for a spot in the quarter-finals.

Berdych, who defeated five-time winner Roger Federer on his way to the semi-finals last year, eased past French 31st seed Julien Benneteau, 6-0, 6-3, 6-2.

Wawrinka, a quarter-finalist in 2010, got past unseeded Cypriot Marcos Baghdatis, the former world number eight but now down at 53 in the world, 6-3, 6-2, 6-7 (1/7), 7-6 (9/7).

Baghdatis, the 2006 Australian Open runner-up, has now lost all three meetings with Wawrinka.

The bearded Cypriot saved four match points before falling in a big-hitting clash on Louis Armstrong Stadium, which saw a total of 100 winners unleashed.

Berdych hit 36 winners and 11 aces in the contest with Benneteau, which finished six minutes short of two hours.

"It was a bit hot, a bit humid, but otherwise the tennis was good," said Berdych, who has made the quarter-finals at the Australian Open and Wimbledon this year.

"I managed to stay focused from the first point until the last. There were no ups and downs, just took all my chances that I had, and won in straight sets."

Wawrinka has a 6-5 career lead over former Wimbledon finalist Berdych, having won their last meeting on clay in the Madrid Masters semi-finals this year.

"He's not really happy to play against me. He doesn't like my game," said Wawrinka of Berdych.

"I know if I'm if fit and if I play well, I have some chance."

Later Sunday, top seed Novak Djokovic, the 2011 champion but beaten by Murray in last year's final and in this year's Wimbledon title match, takes on unseeded Joao Sousa, the first Portuguese player to make the third round in New York.