US Open PHOTOS: Venus ousted; Murray opens defence with dominant win

Venus Williams was knocked out of the US Open on Wednesday, beaten 6-3, 2-6, 7-6 by China's Zheng Jie after the pair slugged it out for more than three hours.

The 33-year-old American, the second oldest player in the women's singles draw, staged an incredible fightback to push the match into a deciding tiebreak but ultimately came up just short as she suffered her third successive second round exit at Flushing Meadows.

Williams was once the undisputed queen of tennis in New York, winning the US Open in 2000 and 2001, but has struggled with health problems in recent years.

She provided a glimpse of her best when she beat Belgium's Kirsten Flipkens in the opening round on Monday but was always in trouble against the 30-year-old Zheng, whose best achievements have come in doubles.

With her hair braided and dyed a deep purple and with her fingernails polished in the same vivid fuschia, Williams made a shaky start.

The former world number one committed 15 unforced errors and served four double-faults to lose the opening set, which was interrupted by a long rain delay.

She fought back to win the second and recovered from 4-1 behind in the third through sheer force of will.

But just when she got back on level points in the tiebreaker, Williams made two successive errors to hand victory to Zheng, who matched her best performance at the US Open by reaching the third round.

"It's unbelievable I can beat her," Zheng said in a courtside interview.

"I think this is very good for me and gives me more confidence for the next one."

Andy Murray was not happy about having to wait until Wednesday night to open defence of his US Open title but the Briton was quite pleased with the result after delivering a masterly thrashing of Michael Llodra.

Wimbledon champion Murray, whose starting time was further delayed after four hours of rain delays had stalled proceedings at Flushing Meadows, raced through an entertaining 6-2, 6-, 6-3, 98-minute drubbing of the 49th-ranked Frenchman on centre court.

"The rallies were quick, sharp. Wasn't much time between points. He was playing quickly on his serves in between points," the third-seeded Scot rattled off like winners from his racquet.

"It was a fairly, I thought, high standard match. Lots of reactions and dropshots, and definitely tested my movement today. I thought I moved well. I didn't make too many errors.

"It was a solid match."

China's Li Na has waited a year for another crack at Britain's Laura Robson and got her wish on Wednesday as their second-round victories set up a third round US Open showdown.

Robson, 19, eliminated Li in the third round at Flushing Meadows last year.

The fifth-seeded Li beat Sweden's Sofia Arvidsson 6-2, 6-2 on Arthur Ashe Stadium court and Robson, seeded 30th, advanced with a 6-4, 7-6 victory over Caroline Garcia of France, winning the second-set tiebreak 7-5.

"After last year I think both players improved a lot. I'm really looking forward to playing against her," Li told reporters about a rematch against former Wimbledon junior champion Robson.

"For sure, really challenging, a lefty, aggressive player. Also, I can prove myself after one year whether I can do better than last year."

Robson said she well remembered their showdown at the 2012 US Open.

"I remember being so nervous when I walked on court," the Australian-born Briton said. "But just fighting through that and just sticking with her.

"I think she made a lot of mistakes in the first set, which helped quite a lot. Hopefully she'll do that again."

Li, 31, believes she has improved since taking on Carlos Rodriguez as her coach last year, although it has been a process.

Former champion Juan Martin del Potro outslugged a gritty Guillermo Garcia-Lopez in a contentious four-set match decided by a tiebreaker to reach the second round.

Argentine Del Potro, who won his only grand slam at Flushing Meadows in 2009, beat the 74th ranked Spaniard 6-3, 6-7 (5), 6-4, 7-6 by taking the climactic tiebreak 9-7 on his fourth match point.

The towering sixth seed had all he could handle from an inspired Garcia-Lopez in a match that saw the players bicker on a changeover as Del Potro complained about treatment his opponent was receiving on his left leg.

Garcia-Lopez, who had several extremely close calls in his favour reversed by challenges, kicked at his towel in disgust after a costly reversal during the tiebreaker.

The four hour, 13 minute marathon actually lasted twice as long with two rain delays totalling more than four hours further extending the match.

Del Potro will next play 2001 US Open champion Lleyton Hewitt of Australia, who beat American wild card Brian Baker 6-3, 4-6, 6-3, 6-4.