Serena and Venus Williams made smooth progress on the opening day of the US Open in New York.
Twice former champion Serena began her Flushing Meadows campaign with a 6-1 6-3 defeat of Yung-Jan Chan.
The injury-hit eighth seed was never at her best in only her third match since Wimbledon but eventually secured a meeting with Catalina Castano.
Wimbledon champion Venus was more impressive as she swept past Japan's Rika Fujiwara 6-3 6-1.
"I'm feeling really good," said Serena of her ankle and knee problems. "I'm not feeling too much pain out there. I didn't get tired."
Venus, who plays Maria Kirilenko next, said: "It was a good day.
"I wasn't able to get exact rhythm or hit as many balls as I'd like to but it's always good to be in the second round."
Kim Clijsters gave early evidence that she will be a real threat with a convincing win in her opening match.
The Belgian is many people's favourite to win her first Grand Slam title in the next fortnight, and she thrashed Germany's Martina Muller 6-1 6-2.
"Having this momentum coming in is good for my confidence, it's helped a lot," said Clijsters afterwards.
"But I never look ahead in a Grand Slam. A lot of things can change."
Clijsters will take on Fabiola Zuluaga of Colombia in round two.
Japan's Akiko Morigami left Flushing Meadows in a wheelchair after being overcome by heat against Australian Nicole Pratt as temperatures soared above 30 degrees Celsius.
Elsewhere, Daniela Hantuchova, seeded 20, beat Camille Pin of France 6-3 6-1.
Nicole Vaidisova was the first woman to reach the second round after a 6-3 6-0 win over fellow Czech Kveta Peschke.
The 16-year-old, seeded 26th, will now take on China's Jie Zheng who came through 6-2 3-6 6-0 against Iveta Benesova, also of the Czech Republic.
Another teenager, 17-year-old Ana Ivanovic of Serbia and Montenegro, seeded 18th, beat American Lindsay Lee-Waters 7-6 (7-5) 6-3.
American Laura Granville upset number 22 seed Silvia Farina Elia of Italy 6-2 6-1, and Maria Elena Camerin beat number 21 seed Darina Safina of Russia 6-3 6-7 (5-7) 6-3.