By Simon Cambers

NEW YORK (Reuters) - Former world number one Serena Williams said she was not worried about the relatively limited match practice she has managed going into next week's U.S. Open.

The American was off the Tour for six months with a knee injury after the Australian Open and has played only two events this summer.

Her ranking has slipped to 90 but having reached the semi-finals in both Cincinnati and Los Angeles, Williams said she was ready for another crack at a title she has won twice before.

"I am really excited," she said. "I've had two solid tournaments. I was able to get some solid results under my belt. I'm really looking forward to these two weeks.

"I am hitting well. As long as I stay healthy, I'll be fine."

Williams has a tough draw in New York with a possible third-round match with in-form Serbian Ana Ivanovic her first big obstacle.

World number one Amelie Mauresmo, a rejuvenated Martina Hingis and former Wimbledon champion Maria Sharapova are also potential blocks in her path to the final.

"I haven't looked at the draw," Williams said. "That's not me. At the end of the day you're going to have to play everybody. I knew going in here I wouldn't be seeded, so I was fine with that. I have no worries, I don't care, it doesn't matter."