Tommy Robredo and Elena Dementieva won their opening matches at the Pilot Pen on Monday, and Americans also made a mark before rain stopped play.
Robredo, the No. 2-seed in the men's draw, advanced to the third round with a 6-4, 6-4 win over Marc Gicquel of France.
The Spaniard, ranked No. 8 by the ATP, played four consecutive clay-court tournaments following Wimbledon, and said he needs these matches to get ready for the U.S. Open next week.
"On hard court, I wasn't winning a lot of matches these last two weeks," he said. "For me, I think it's good to be here and get the confidence back."
Dementieva, seeded sixth in the women's draw, beat Mara Santangelo of Italy, 6-2, 3-6, 6-0. The Russian used strong ground strokes to overpower Santangelo and overcome nine double faults.
"Sometimes I feel like I need to take more time before I go to serve," she said. "I feel like my serve is getting better, but when you play under pressure, sometimes it's difficult."
The only other seeded woman to play Monday, No. 7 Sybille Bammer, beat American Meghann Shaughnessy, 6-4, 6-2. American Ashley Harkleroad advanced over Tatiana Poutchek of Belarus, 6-1, 6-0
On the men's side, Americans Mardy Fish and Vincent Spadea also won.
Fish moved into the third round with a 6-7 (4), 7-5, 6-0 win over Filippo Volandri of Italy. Volandri was up 5-3 in the second and serving for the match, when Fish reeled off 10 straight games.
"This is the time that the Americans want to shine the most," he said. "This is an important tournament for me. It's nice to get on a little bit of a roll. Winning always helps your confidence, and confidence is a major part in tennis."
Spadea advanced with a tough 6-2, 5-7, 7-5 first-round win over Russian Evgeny Korolev. The colorful 33-year-old decided to celebrate the victory by rhyming his way through the post-match news conference.
"It's great to have a high-level intensity match, especially when I win it, and I grin it," he said. "Not all of us can be sittn' here on Saturday afternoon, with a silver spoon, so I might as well just focus on every celebration and take it one step further."
American rookie John Isner was to take center stage later in the featured match on stadium court against German Benjamin Becker, but his match was postponed by rain.
Play was suspended at about 7:20 p.m. in the second game of the match between Sania Mirza of India and Anabel Medina Garrigues of Spain, with Medina Garrigues leading 1-0.
Also in the men's draw, Albert Motanes of Spain, defeated Teimuraz Gabashvili of Russia, 6-4, 6-4; Jose Acasuso of Argentina defeated Olivier Rochus of Belgium, 6-1, 7-6 (7); Julien Benneteau of France defeated Spain's Oscar Hernandez, 6-2, 6-2 and France's Arnaud Clement defeated Kevin Anderson of South Africa, 6-1, 6-4.
On the women's side, Agnes Szavay beat Samantha Stosur 6-2, 6-4; Emilie Loit beat Dominika Cibulkova 6-0, 7-5; Virginia Ruano Pascual of Spain defeated Olga Poutchkova of Russia, 7-6 (4), 6-1; and Alona Bondarenko of the Ukraine defeated Belarus' Olga Govortsova, 6-3, 7-6 (2).