U.S. Open 2011: Watch Out for Serena Williams (Tennis)

Serena Williams has already won a title since returning to competition after missing nearly a year and she sent a warning shot to her rivals when she said on Tuesday she is still not in top form.

After missing nearly a year of competitive tennis because of injuries and health problems, Williams captured the Stanford Classic in her third tournament back and followed that with a solid opening match at the Toronto Cup Tuesday.

But despite barely breaking a sweat in a 6-0 6-3 win over Ukraine's Alona Bondarenko where she recorded seven aces and captured 24 of the opening set's 28 points, Williams feels she has more gas in the tank for the August 29-September 11 U.S. Open.

"I definitely want to get better," Williams told reporters after disposing of Bondarenko in 46 minutes. "I would hate to be grand slam ready right now seeing as the U.S. Open is not right now so I'll try to peak at the right time."

The 13-times grand slam winner has shown little rust since returning and was even considered by many to be the favorite at Wimbledon, where she breezed into the last 16 before losing in the fourth round in her second tournament back.

Williams wants to reclaim her status as the dominant force in women's tennis and the 29-year-old American has decided expending less energy while on the court could be the key.

She followed that plan perfectly against Bondarenko as Williams had her opponent running back and forth along the baseline while she barely broke a sweat.

"I'm definitely a lot healthier obviously than I have been before and I am not using as much energy as I used to," the former world number one said. "Maybe I have evolved."

(Reuters)