Former U.S. Open champion Maria Sharapova kick started the Olympus U.S. Open series at the Western & Southern Financial Group Women's Open being played in Cincinnati, USA with an upset win over compatriot and San Diego champion Svetlana Kuznetsova, winning the 6-4, 1-6, 6-2 match in two hours and 12 minutes of fantastic tennis.

The day turned out to be bad for another seeded Russian, No.15 Nadia Petrova who lost her opening match to American Wild Card Christina McHale. After losing the first set in a tie-break 7-6(4), Petrova retired from the match due to heat illness, while trailing 5-3 in the second.

"I'm just excited to move onto the next round," McHale said. "I was just trying to stay cool in the heat. I drank a lot, put some ice packs on my neck, changed my outfit after the first set. I think I handled it well. I remember the heat in Australia being like this last year."

2009 U.S. Open semifinalist Yanina Wickmayer also made it to the next round with a convincing 6-2, 6-2 win over qualifier Greta Arn.

"It was hot and humid out there but I handled it well," said Wickmayer. Today I played one of my best matches of the year. I'm really happy with my form."

The Belgian was later joined by Italian Flavia Pennetta, who took out Chinese star Jie Zheng 6-4, 6-2. Seeded 11 at the WTA premier event, Pennetta is hoping to win the second title of the year after her triumph in Marbella earlier this season on clay.

The American fans' hopes were dashed when teenage prodigy Melanie Oudin crashed out of the event with a disappointing loss at the hands of Russian Elena Vesnina, losing the match in straight sets with a 2-6, 3-6 scoreline.

About the huge level of expectations from home fans after her magical quarterfinal run at the U.S Open last year, Oudin said - "I'm hoping the hype won't be that bad this year, but I have a feeling it's going to be. People are going to expect I can do it again. But this year I'm going to go into it just like last year - that's how I did so well. No expectations. Last year I saw my draw before the tournament and my coach looked at me and said, 'To win, you have to beat six Russians and a Williams sister.' It was a joke. To beat them last year was amazing, but I had no pressure on me and I just went for it."