World number one Serena Williams has pulled out of next week's Sony Ericsson Open due to a knee injury, organizers said on Friday.

Williams, a 12-time Grand Slam winner, hasn't played since completing her title run at the Australian Open earlier this year. She has been hampered with the left knee injury.

Defending U.S. Open champion Juan Martin del Potro also pulled out Friday with a wrist injury.

"Obviously, we are disappointed when any of the top players pull out,'' tournament director Adam Barrett said. "When you are talking about one of the most prolific players in the game, a player like Serena, it is extremely disappointing, especially for the fans who won't get to see her.


"We want the best players versus the best players, but we still have a great field with many of the top players in the world. Only difference is this year, we know Serena won't win it. But if a player isn't at 100 percent and can't play their best, it's better for them to sit out. We're here for the long haul. I'd rather see Serena have a long career than have her play in Miami two weeks and jeopardize her health.''

As for Del Potro, Barrett said the Argentine fans in particular will miss out.

"He's a very exciting player and has been a big draw here,'' Barrett said. "The good news is, he's young, and I expect him to come back next year and for 10 or 12 years after that. You're always going to lose some players to injury, but that doesn't diminish the tournament.''

Earlier in the week, former No.‚1 players Maria Sharapova and Dinara Safina, and Nikolay Davydenko all withdrew.


(via The Miami Herald, photo/AP Photo)

Serena Williams, Juan Martin del Potro withdraw from Sony Ericsson Open