Novak Djokovic overcame an ankle injury to defeat Frenchman Arnaud Clement 6-3 6-3 6-4 in the first round of the US Open on Wednesday.
Fifth seed Russian Nikolay Davydenko also advanced to the second round courtesy of an easy 6-3 6-3 6-3 victory over Israel's Dudi Sela.
Third seed Djokovic, who lost to Roger Federer in last year's final, entered this hardcourt Grand Slam as one of the favourites to dethrone the four-time defending champion.
The 21-year-old Serb coasted through his first two sets, mixing his powerful serve with a barrage of precise groundstrokes.
But an eerie silence fell upon Arthur Ashe Stadium in the fourth game of the third set when Djokovic hyper-extended his left ankle while planting himself for a forehand shot.
The reigning Australian Open champion doubled over on his hands and knees before making his way to the sideline, where a trainer administered tape and a pain-numbing spray to his ankle.
Djokovic appeared slightly troubled after the delay, as Clement drew even at 4-4, but he persevered to reach the second round for the fourth time in four career attempts.
Davydenko was making his first appearance in a Grand Slam since his opening-round upset at Wimbledon in June, when he was defeated in straight sets by Benjamin Becker.
Davydenko followed up that disappointing performance with a pair of early exits at the ATP Masters Series events in Cincinnati and Toronto. He also was upset by Paul-Henri Mathieu in the second round of the Beijing Olympics.
But Davydenko looked outstanding against his feisty Israeli opponent.
"It was very surprising," said Davydenko, who has suffered nine first-round losses in majors since 2001.
"I played good for the first round, because I'm always nervous and my confidence is not so great just in the beginning of tournaments."
"But I played good all three sets. I was fighting good and I had very good concentration."
Davydenko converted six breaks, including three in the third set, in a match that lasted two hours and three minutes.
The world No.5 Davydenko moved on to a second-round match with Argentina's Agustin Calleri, who defeated American Austin Krajicek in straight sets. The Russian has won all four of his previous meetings with Calleri, the world No.49.
Andy Roddick began his quest for a second US Open title with a comfortable straight-sets victory over Fabrice Santoro.
Roddick, who won the hardcourt Grand Slam in 2003, has struggled in the major championships this year, falling out of the Australian Open in the third round, Wimbledon in the second, while he did not participate in the French Open.
But the eighth seed had no such trouble in dispatching Frenchman Santoro 6-2 6-2 6-2 at Arthur Ashe Stadium.
Roddick, who has advanced to the quarter-finals or better in six of the last seven years at Flushing Meadows, broke world No.60 Santoro in the opening game and recorded a further break in taking the first set in 25 minutes.
Roddick, who turns 26 on Saturday, was untroubled on his own serve and recorded two breaks in each of the second and third sets to complete an easy win in one hour 26 minutes.
Roddick will next face Ernests Gulbis of Latvia, a straight-sets first-round winner over Thomas Johansson.
Other seeded winners were Nicolas Almagro, Jo-Wilfried Tsonga and Eduardo Schwank, while American Sam Warburg was the only unseeded winner from the early portion of the schedule.