Serena will play with a black Wilson (K) Factor limited-edition racket and Venus will compete with a white version featuring 22-carat gold leaf laid into the frame.

"I can't think of a better place to play with a racket made with real gold than Wimbledon," said Serena, who won the Grand Slam in 2002-03.

The sisters switched to Wilson at the start of the season, and Serena won the Australian Open in January.

"We both started out our tennis careers with Wilson rackets, and our relationship with the brand is very special," said Venus, who won Wimbledon in 2000-01 and 2005.

The Williams sisters will donate 10 autographed rackets for auction by The Breast Cancer Research Foundation (BCRF), a not-for-profit organization that supports clinical and genetic research on breast cancer.

Only 650 rackets will be available this summer, with a percentage of every racket sold benefiting BCRF.