NEW YORK, Aug. 30 -- Top seeds Novak Djokovic and Rafael Nadal both advanced into the second round of U.S. Open, while China's French Open champion Li Na subsided in the first round on Tuesday.
Nadal, the defending U.S. Open champion and this year's second-seeded player, didn't turn in a starring performance, but he managed through Kazakhstan's Andrey Golubev 6-3, 7-6 (1) and 7-5 in almost three hours.
Djokovic enjoyed a comfortable walk through into the second round as his opponent Conor Niland retired trailing 6-0, 5-1 for food poisoning, who threw up and pulled out of the tournament in just 44 minutes.
American favorite contender Serena Williams, playing her first match in New York for two years because of injuries, powered through the night session match 6-1, 6-1 over Serbian Bojana Jovanovski in 56 minutes.
Fifth-seeded Li suffered the second successive opening round exit at the Flushing Meadow, after committing 54 unforced errors, 35 more than her 53th-ranked opponent Halep. The 19-year-old won the match in 6-3, 7-5.
"I was feeling tennis just too tough for me now," said Li. "I want to dewell after Roland Garros, but always lose early. Now I even lose all the confidence on the court."
Golubev, who was ranked 98thin the world and who had gone through a stretch of losing 17 straight matches this season, was leading Nadal, 4-2, in the second set after breaking the Spaniard at love and was making Nadal cranky by pounding winners from both sides and bringing Nadal forward with tricky drop shots.
"I was a little lucky to win in straight sets," Nadal said. "He was a very difficult player to play. He played very fast."
Li's elimination marked a second round of U.S. Open without a reigning Grand Slam singles champion remaining, just the first since 1971.
On Monday, the Wimbledon champion, Petra Kvitova from Czech Republic, also made an early exit.
Caroline Wozniacki, the women's world No. 1 demolished unseeded Spaniard Nuria Llagostera Vives 6-3 6-1.
No. 4 Victoria Azarenka wasted little time in dispatching Johanna Larsson of Sweden 6-1, 6-3.
In men's draw, fifth-seeded David Ferrer rallied from a set down to beat 78th-ranked Igor Andreev, who committed 53 unforced errors.
The Spaniard won 2-6, 6-3, 6-0, 6-4. He hasn't lost in the first round at a major tournament since 2005. Ferrer had 14 unforced errors in dropping the first set, then had only 24 the rest of the way.
Jo-Wilfried Tsonga of France, the 11th seed, went through Lu Yen-Hsun of Chinese Taipei, 6-4, 6-4, 6-4, while 19th-seed Spaniard Fernando Verdasco fought back from a set down, dismissing Jarkko Nieminen of Finland, 3-6, 6-4, 6-1, 6-4.
Other seeds progressed were 17th-seeded Jurgen Melzer of Austria, beating Eric Prodon of France, 6-2, 7-6(4), 6-2; 30th-seeded Ivan Ljubicic of Croatia, dispatching Blaz Kavcic of Slovenia, 7-6(5), 3-6, 6-1, 7-5 and 14th-seeded Swiss Stanislas Wawrinka, who rallied past Maximo Gonzalez of Argentina 3-6, 6-4, 6-1, 6-3.
Russia's Nikolay Davydenko powered off 32th-seeded Ivan Dodig of Croatia 6-7(6), 6-3, 6-0, 2-6, 6-2.
Another Russian Mikhail Youzhny, seeded 16th, become the highlight victim on Tuesday, losing to Ernests Gulbis of Latvia 6-2, 6-4, 6-4.