Elena Baltacha bundled out as British players struggle in Maryland

Sixth seed Elena Baltacha was dumped out of the Citi Open in College Park, Maryland, as she lost her second-round match against Virginie Razzano in straight sets.

The British No?1, who beat Yaroslava Shvedova in the first round, won just one point on her second serve in the second set as she slipped to a 6-4, 6-2 defeat.

Heather Watson also crashed out, left to rue missed opportunities as she lost 3-6, 7-5, 6-1 to Canada's Stephanie Dubois in her second-round match. The British No?2, who won the only previous meeting between the two earlier this year, was ruthless as she took the first set, but could not take her chances in the second, converting only one of ten break points.

Dubois, ranked 13 places below Watson, then ran away with the third set to book her place in the quarter-finals of the Maryland event.

There was further disappointment for Watson as she lost her doubles quarter-final with Anne Keothavong 7-5, 6-3 against Olga Govortsova and Alla Kudryavtseva.

Second seed Nadia Petrova brushed aside 17-year-old Canadian wildcard Eugenie Bouchard 6-2, 6-2, while fifth seed Bojana Jovanovski was forced to battle a little harder as she triumphed over America's Jill Craybas, 6-4, 5-7, 6-4.

In the day's other match, Zhang Shuai was forced to retire due to a heat-related illness after losing the first set 6-4, sending America's Irina Falconi through.

At the Bank of the West Classic in Stanford, California, Serena Williams set up a quarter-final meeting with Maria Sharapova when she beat Russian Maria Kirilenko 6-2, 3-6, 6-2.

"I'm sure we'll both go out and do the best each of us can," Williams said about the clash of the former world No 1s. "It's nothing personal. It's my job and I want to get paid. I leave it on the court." Meanwhile, American player Robert Kendrick was yesterday suspended for a year by the International Tennis Federation after testing positive for a banned stimulant at the French Open.

The ITF said the 31-year-old tested positive for methylhexaneamine on 22 May.

Kendrick said the stimulant got into his system because of a capsule he took to combat jet lag. He denied he was trying to enhance his performance. Kendrick lost in the first round at Roland Garros. The ITF accepted his account, but said a player is responsible for any banned substance in his body. His suspension runs until 21 May, 2012.

Kendrick reached a career-best ranking of 69th in 2009 and is currently 105th.Methylhexaneamine has been at the centre of numerous doping cases in recent months.

The World Anti-Doping Agency recently loosened the classification of methylhexaneamine to the "specified stimulant" list, covering drugs that are more susceptible to inadvertent use and can carry reduced penalties.

Two South Africa rugby players - Bjorn Basson and Chiliboy Ralepelle - and Hamilton football player Simon Mensingo recently tested positive for the stimulant.

Last year, a dozen Indian athletes - including wrestlers, weightlifters and swimmers - tested positive for methylhexaneamine just before the Commonwealth Games and were banned.