Grigor Dimitrov wins in three sets
The 14th-ranked Dimitrov, a Bulgarian who at 22 is the youngest player in the top 20, did not take well to the red-and-white towels at the Foro Italico.
"They're new and they don't absorb any sweat," he said. "Three or four times I was about to lose my racket. I asked several times (for all-white towels) but they told me, `We don't have it."
In women's play, Sam Stosur beat Wimbledon runner-up Sabine Lisicki 6-3, 6-3; 11th-seeded Ana Ivanovic defeated Italian wild-card entry Karin Knapp 6-1, 6-1; 12th-seeded Flavia Pennetta got past Yvonne Meusburger of Austria, 6-2, 6-3; and 16th-seeded American Sloane Stephens rallied past Bojana Jovanovski of Serbia 3-6, 6-3, 6-3.
The eight top-seeded players have first-round byes.
Second-ranked Novak Djokovic is back after withdrawing from last week's Madrid Open with a right wrist injury and Roger Federer was out on the practice courts after also taking last week off to welcome the birth of his second set of twins.
Top-ranked and defending champion Serena Williams, however, wouldn't commit to playing as she waits to see how her injured left thigh feels.
"I'm taking it a day at a time. We'll see as the week goes on. I have the rest of the day off and I'll see how I feel tomorrow," Serena said. "I hit some balls today a little bit so I'm going to see later tonight how it feels."
Serena withdrew before her quarterfinal match in Madrid, where she had her thigh heavily bandaged and said the injury occurred during a first-round victory over Belinda Bencic.
Rome is the last key clay-court warmup before the French Open starts in two weeks.