World number ones Roger Federer and Justine Henin made little efforts to advance into the second round of the US Open on Monday.
Three-time defending champion Federer, seeking his 12th Grand Slam singles crown, opened the year's final Grand Slam event with a 6-3, 6-2, 6-4 victory over 320th-ranked American Scoville Jenkins in 92 minutes.
"I'm happy to have won my first one. I'm happy I'm through," Federer said. "It always feels like a bit of a relief. Now I can relax a little maybe."
Henin, who is nursing a sore shoulder, disposed of 145th-ranked German Julia Goerges 6-0, 6-3 in just over an hour.
"I'm glad to win that way," said Henin. "I was a bit concerned the last few days with my shoulder. It's getting better but still a little scary."
Eighth seed Serena Williams, who won her eighth Grand Slam title in January at the Australian Open, showed some rust from a long layoff due to a thumb injury but defeated Germany's Angelique Kerber 6-3, 7-5.
The younger Williams sister had not played since a Wimbledon quarter-final loss to Henin.
Reigning Wimbledon champion Venus Williams downed Hungarian qualifier Kira Nagy 6-2, 6-1 in 54 minutes.
Venus Williams next plays Romania's Ioana Raluca Olaru, who ousted American Ashley Harkleroad 7-5, 1-6, 6-4. Serena Williams will next meet Italy's Maria Elena Camerin, who beat Russian Tatiana Poutchek 6-3, 7-6 (7-4).
The second round opponent for Federer is another qualifier, Paul Capdeville. The Chilean outlasted Germany's Rainer Schuettler 5-7, 6-3, 6-7 (4/7), 6-4, 6-3.
Henin, seeking a seventh Slam title after taking her fourth French Open title in June, next plays Tsvetana Pironkova of Bulgaria who defeated Olga Poutchkova of Russia 6-3, 6-4.
Britain's Andy Murray, who missed Wimbledon and the French Open, made a triumphant Grand Slam return from a wrist injury by defeating Uruguay's Pablo Cuevas 6-2, 6-3, 6-0.
Russian fourth seed Nikolay Davydenko and Serbian third seed Jelena Jankovic, both 2006 US Open semi-finalists, advanced in straight sets, as did Serbian fifth seed and French Open runner-up Ana Ivanovic.
Cypriot 18th seed Marcos Baghdatis was the top-ranked player to lose on day one, losing to Max Mirnyi of Belarus 6-3, 7-5, 3-6, 7-6 (8/6). Spanish 21st seed Juan Carlos Ferrero lost to countryman Feliciano Lopez 6-3, 6-4, 6-4.
Tuesday's program features defending champion Maria Sharapova, Australia's Lleyton Hewitt, US seeds Andy Roddick and James Blake.