ROME -- Venus Williams pulled out of her match against Anna Kournikova at the Italian Open Tuesday night because of a wrist injury, with the stadium already half-full for the highly awaited encounter.

The world's top-ranked player said she injured her right wrist while picking up her bag at practice this week. The 21-year-old American appeared on court and apologized to the crowd minutes before the match was to begin.

Williams said she told the WTA about her withdrawal a half hour before the match was scheduled to start.

"It happened this week," Williams said at a news conference later. "This morning in practice it hurt and then during the day it got worse with more swelling. I could have played with the pain but it did not seem correct.

"Hopefully it won't be very serious. Hopefully I'll be able to practice soon. I'm just going to take some time off and maybe finally see something in Rome."

The injury comes at a bad time for Williams, with the French Open less than two weeks away.

"It really makes me somewhat nervous about the French, that I won't be able to play this week, that I'll have two weeks that I can't play a tournament," she said.

Last year, Williams pulled out of a semifinal match against her sister Serena in similar fashion at a tournament in Indian Wells, Calif.

Asked Tuesday if she should have announced her injury sooner, Williams replied: "No."

"I did notice it at the time, but then I was OK," she said. "But right now, the same symptoms and same pain I had then is the same that I'm having now."

Tournament officials released a statement saying the injury had been certified by the WTA but that the tournament doctor and a WTA trainer would re-evaluate the injury on Wednesday.

"I think I'm going to stay here and support Serena, then hopefully start practicing on clay," Williams said.

Williams, entering her seventh straight week at No. 1, was also entered in the doubles draw with her sister in the $1.22 million event.

The clay-court tournament is a major tuneup for Roland Garros, which begins May 27.

Lilia Osterloh of the United States took Williams' place in the draw.