Defending champions Murray and Williams advance at US Open

Defending champion Andy Murray ground his way past Uzbekistan's Denis Istomin with a 6-7, 6-1, 6-4, 6-4 victory in the early hours of this morning to reach the quarter-finals of the US Open where he will face Stanislas Wawrinka.

Murray struggled to get out of the blocks in the first set and trailed 5-3 after two forehand errors handed Istomin the break. Although Murray immediately broke back, he lost out in the tiebreak, with a double fault and a slice into the net allowing Istomin to serve out the set.

After levelling the match, the Scotsman displayed some clear signs of frustration in the third set but finally took control by breaking Istomin in a marathon seventh game after the enterprising Uzbek had saved three break points.

There was never any doubt from then as the Wimbledon champion wrapped up the match in a little over three hours. Murray said the cool and slightly gusty conditions in Arthur Ashe Stadium were a factor in his slow start to the night match.

“It was definitely tough. It’s pretty breezy out there. Quite a strong breeze. Both of us were struggling with our timing early on,” he said. “I thought we played some entertaining points. Sometimes when it’s windy like that, you get some fun points.

“I just started trying to dictate the points. I tried to use my forehand a little bit more,” he added.

Earlier in the day, defending champion Serena Williams walloped Spain's Carla Suarez Navarro 6-0 6-0 to race into the semi-finals. Top seed Williams served up the dreaded "double-bagel" in a quick-fire 52 minutes to set up a clash with fifth seed Li Na, who earlier became China's first US Open semi-finalist by beating Russian Ekaterina Makarova.

“Honestly she’s a great player,” said Williams, blaming the conditions for the Spaniard’s plight on her 25th birthday. “The conditions today were so tough. It was not her best tennis today.”

The outcome may have been more about the world number one being at something close to her best, however. Williams won 88 per cent of her first serves, rifled in four aces, smacked 20 winners to three for her opponent, and won 53 points to just 18 for the 18th seed.

“I played really good. I was just more focused than anything,” she added, stopping short of calling it her best. “I like to believe there is room for improvement.”

It was only the second love-love victory in a US Open women's quarter-final dating back to 1968, and first since Martina Navratilova subjected Manuela Maleeva of Bulgaria to the same embarrassment in 1989. At 31, Williams is campaigning to become the oldest US Open women's winner since tennis turned professional in 1968.

She has lost just 13 games from her five matches so far and said she has been balancing fun with work at Flushing Meadows.

“I’m having a blast this week,” said Serena, who is also still alive in women’s doubles with older sister Venus. “I have just really been enjoying my matches. For me, I have to stay in that moment of fun, but intensity, but calm. If I can try to do those three things, it works out.”