Serena Williams could have to get past sister Venus Williams if she is to reach the US Open final and win a 12th Grand Slam title.

The three-time US Open champion, seeded second behind Dinara Safina for the final grand slam of the year starting on Monday, was on Thursday put in the same half of the draw as her third-seeded sister, putting them on course for a semi-final clash.

The siblings contested the Wimbledon final in July for the second year in a row, Serena winning in straight sets to claim her second Grand Slam title of the year having landed the Australian Open in January.

Those are her only two titles this year but Serena said there was no particular reason she appeared to succeed in the Grand Slams rather than regular WTA Tour events.

"I don't know, I just really love playing in grand slams, big tournaments," she said.

"I just love stepping out on any court but I don't seem to have much luck outside of the Grand Slams.

"It's obviously a tough tournament coming up, I'm just going to do the best that I can do and most of all relax."

Serena also defeated Venus on the way to her 2008 title at Flushing Meadows, winning their quarter-final but her title defence begins against fellow American Alexa Glatch, a wild card, with Russia's Vera Zvonareva her highest seeded opponent at number seven in their quarter of the draw.

Venus Williams has No.8 Victoria Azarenka of Belarus as her highest ranked rival in her quarter but her path to the last four could be further complicated by having 2005 champion Kim Clijsters, granted a wild card as she continues her comeback in the game, as a potential fourth round opponent.

Whether she achieves her 12th Grand Slam success this month or not, Serena said she was confident she would win one and therefore equal Billie Jean King's career total.

"That would be awesome," she said. "Obviously that's anyone's goal that has the grand slam titles that I have but regardless as to whether that happens this next two weeks or in the future I still think I have a great chance of that happening in my career. I hope it does happen.

Women's top seed Safina, searching for a first Grand Slam title, has been drawn to play Australian wild card Olivia Rogowska in the first round and is seeded to face No.5 Jelena Jankovic, last year's runner-up, in the quarter-finals.

No.4 Elena Dementieva is seeded to face fellow Russian Safina in the semi-finals, although former champion and compatriot Maria Sharapova, seeded 29th, is a possible third round opponent for 2008 Olympic gold medallist Dementieva.