Los Angeles - Former world number one Serena Williams will open her summer hard-court season at the WTA tournament in San Jose, California, July 30-August 5. 

"I am looking forward to opening my summer season at the Mubadala Silicon Valley Classic and competing in the new venue," Williams, a 23-time Grand Slam champion, said in a statement posted on the tournament website. 

"This tournament plays an historic role in women's tennis, and as a California native the fans in the Bay Area have always been incredibly supportive." 

The tournament formerly known as the Bank of the West Classic and held in Stanford, California, is moving to the campus of San Jose State University this year.

Five-time Grand Slam champion Maria Sharapova and defending champion and US Open finalist Madison Keys have also committed to play in the event that is part of the build up to the US Open. 

On Wednesday, the 36-year-old Williams pulled out of next week's Italian Open in Rome, a tournament she has won four times. 

That followed her withdrawal from Madrid and raised doubts as to whether she'll be ready for the French Open in Paris May 27-June 10. 

The American tennis star made her return to the court in February, six months after giving birth to her daughter Olympia, but has admitted she is struggling to get fully fit.