|Despite the late start Swiss Roger Federer was back to his best at the U.S. Open in New York [GALLO/GETTY]
Roger Federer and Serena Williams beat the weather and their opponents to storm into the quarter-finals of the U.S. Open on Monday and send an ominous warning to the current world number ones about their intentions for the last grand slam of the year.
It was just likes old times for the greatest players of their generation as they turned in masterful displays on a day when Novak Djokovic and Caroline Wozniacki both toiled but survived.
Federer demolished Argentine baseliner Juan Monaco 6-1 6-2 6-0 in a fourth round clash that began just before midnight but ended before an approaching storm drenched Flushing Meadows.
Williams, playing during the day when the wind was blowing hard, breezed past Serbia's Ana Ivanovic 6-3 6-4 to close in on what could be the greatest achievement of her incredible career.
"It's really important for me just to look at the mountain and keep climbing it," said Williams.
"It's really important for me just to look at the mountain and keep climbing it"
Wozniacki won a late-night thriller against former champion Svetlana Kuznetsova of Russia 6-7 7-5 6-1, dispelling the notion that she lacks the predatory instincts to land her first major.
Facing an early exit after losing the first set in a tiebreaker then falling behind 4-1 in the second, she won 12 of the last 14 games and looked as fit at the end as she did at the start.
"I could have played another two or three sets if I had to," the Danish top seed said.
Her next match is against Germany's Andrea Petkovic, who defeated Carla Suarez Navarro of Spain 6-1 6-4, with Williams looming in the semis.
Djokovic also showed his fighting qualities to win a 30-point tiebreaker in his 7-6 6-4 6-2 victory over Ukraine's
Alexandr Dolgopolov to reach the last eight without dropping a single set.
"It was certainly exciting to be part of it but I knew that I needed to win that set," he said.
There were no such problems for Federer, who reached his 30th straight grand slam quarter-final with a breathtaking display that included four aces in a single game.
"I played very well," the Swiss said.
"So it's up to me now to get on a good run for the end of the tournament."
Williams's ability to overcome adversity has helped make her the finest player of her era, and among the best of all time, but when doctors found a life-threatening blood clot on her lungs in March, winning the U.S. Open was the last thing on the American's mind.
| Serena Williams of the US shakes hands with Ana Ivanovic of Serbia after her victory [GETTY]
Yet here she is, riding high on emotion and with momentum building behind her.
"I think I'd like to say it's a bigger mountain like Everest...(but) I don't ever want to get to the top of the mountain. I want to keep being able to reach something," she said.
Williams's next opponent is Russia's Anastasia Pavlyuchenkova, who avenged her agonising loss to Italy's Francesca Schiavone at this year's French Open to win 5-7 6-3 6-4.
It was sweet revenge for Pavlyuchenkova after she blew her chance of a first grand slam semi-finals appearance when she lost to Schiavone in the quarters at Roland Garros after leading 6-1 4-1.
"Of course I was thinking about it," Pavlyuchenkova said.
"But it made me stronger I think."
Djokovic's next opponent is his Davis Cup team mate Janko Tipsarevic, who beat former world number one Juan Carlos Ferrero of Spain 7-5 6-7 7-5 6-2 in a slugfest that lasted almost four hours.
"It means there's going to be at least one Serbian in the semi-finals, which is great for our country," Djokovic said.
The floodlit evening session was delayed by more than an hour and a half after 11th-seeded Frenchman Jo-Wilfried Tsonga needed almost four hours to beat American eighth seed Mardy Fish 6-4 6-7 3-6 6-4 6-2 in an enthralling center court clash.
Tsonga's reward is a quarter-final on Wednesday against Federer.