Serena Williams pulls out of Miami Open

American tennis star Serena Williams has withdrawn from the Miami Open with a left knee injury  in the second round, on Sunday.

The Miami tournament is the second consecutive WTA event in which Williams has been unable to continue, after her retirement from last week's Indian Wells event with illness.

Williams said in a statement: "I am disappointed to withdraw from the Miami Open due to a left knee injury. It was an amazing experience to play at the Hard Rock Stadium this year and I would like to thank the Miami Open for putting on an amazing event.

"I hope to be back next year to play at this one-of-a-kind tournament in front of the incredible fans here in Miami " ,as stated by William.