Djokovic survives thriller

Novak Djokovic illuminated New York's midnight hour with an electrifying performance on Sunday, surviving a 234-minute battle to reach the fourth round of the US Open.

The Serbian third seed soaked up the full force of Marin Cilic's armoury to stay in the hunt for the title with an absorbing 6-7 7-5 6-4 7-6 victory in a contest that ended at 12.48 a.m. (US time).

The 21-year-old squandered two match points in the 10th game of the fourth set but roared through the last 11 points of the match to seal the win when Cilic dragged a service return wide.

Asked on court how he was feeling, the Australian Open champion replied: "You're asking me how I'm doing after a four-hour match, not fresh, for sure.

"Thanks everybody for staying so late for us. I had a very difficult match and even if I lost today, he would have deserved it. He played great."

Djokovic discovered he was in for a long night when set point up in the opening set, he was made to scamper around like a demented bunny only to lose a 31-shot rally.

Cilic, 19, kept up the intensity throughout but eventually was undone by his lack of experience, cracking down 12 double faults to undo his hard work.

Djokovic's next test will be against 15th seed Tommy Robredo.

While Djokovic kept the midnight oil burning, Roger Federer and Jelena Jankovic were enjoying an early night, thanks to their relatively smooth progress during the day session.

After a week of lukewarm performances, four-times champion Federer turned on the heat with a masterful 6-3 6-3 6-2 destruction of Czech 28th seed Radek Stepanek.

Women's world number two Jankovic looked to be heading for another long workout but found her range to end the plucky challenge of Danish teenager Caroline Wozniacki in the fourth round with a 3-6 6-2 6-1 victory.

As temperatures soared on day seven of the hardcourt major, an ailing Marion Bartoli said it was a "miracle" she could battle on for more than three hours in the stifling conditions. She eventually fell 7-6 0-6 6-4 to Austrian Sybille Bammer.

"I had very low blood pressure and very weak pulse and the trainer advised me not to continue, especially because it was so hot," said the 12th seed, who had her pressure checked on court midway through the first set.

While Bartoli wilted under sunny skies, Federer flourished.

In his first two matches, the Swiss master had fallen well short of proving his title credentials as he piled up 66 unforced errors and converted only 11 of 28 break points.

On Sunday, he dazzled Stepanek and 23,000 wide-eyed fans on Arthur Ashe Stadium court when his game clicked into overdrive.

At one point, the Swiss even managed to surprise himself. With his back pinned to the rear wall, Federer leapt high into the air and his slam-dunk mis-hit bounced off a startled Stepanek's racket frame for a winner.

After toying with Stepanek for 96 minutes, Federer threaded a forehand down the line to seal victory and celebrated by punching the air and holding aloft his index finger, as if to remind people "I'm still number one in New York."

Federer chalked up his 30th consecutive victory in New York to set up a meeting with Russia's Igor Andreev.

Another Russian, Olympic champion Elena Dementieva, continued to slice through the draw with a ruthless 6-4 6-1 win over China's Li Na. Next up for her is Swiss 15th seed Patty Schnyder.

Eighth seed Andy Roddick beat Italian Andreas Seppi 6-2 7-5 7-6.

Fourth round: (women) Pennetta bt Mauresmo 6-3 6-0; Safina bt Groenefeld 7-5 6-0. (Men) Fish bt Monfils 7-5 6-2 6-2.