Three-time Grand Slam winner Maria Sharapova continues her comeback from shoulder surgery by competing in the $700 000 Bank of the West Classic which begins on Monday.

Sharapova will have her work cut out for her against a strong field that includes five of the world's top ten, including Venus and Serena Williams.

Sharapova says the support she received from family, doctors and friends helped get her through the shoulder rehabilitation.

"I had a great team around me that kept me really positive," Sharapova said before an exhibition match earlier this week in Los Angeles. "By no means was it easy, an easy flow. Definitely, I had ups and downs. I had days where I had to push myself more than I've ever had to, mentally than physically.

"It all pays off. Obviously just getting to be able to play tennis again is an achievement in itself. Now it's about preparing myself, forgetting about what I went through, just preparing my game, getting back into the form where I was, and even better."

Because of the surgery Sharapova was unable to defend her title at the Australian Open in February. She also missed the Beijing Olympics and the US Open.

The 19-time WTA Tour singles champ is a hit off the court as well as Forbes Magazine recently reported that she earned $22-million in endorsements over the past year.

Her first match in the 32-player Stanford draw will be on Monday against Japanese veteran Ai Sugiyama.

She is hoping for a better showing on the Taube Family Tennis Stadium courts than at Wimbledon where she lost in three sets to unheralded Gisela Dulko.

The tournament also features a 16-team doubles draw that has attracted the Williams sisters.

The pair, who will travel to their home in south central Los Angeles for the following week's LA Women's Championship, rarely play doubles together outside of grand slams.

Serena highlights Tuesday's night session where she will face Chinese star Li Na. Former Stanford champion Venus takes to the court earlier in the day against Canadian wildcard entry Stephanie Dubois.

Past champions include Billie Jean King, Chris Evert, Martina Navratilova, Monica Seles, Martina Hingis and Kim Clijsters.