Serena Williams dethroned defending champion Lindsay Davenport to reach the final of the $14.5 million US Open Tennis Championships in New York yesterday. Williams (17), the seventh seed, kept alive the prospect of an all-Williams final before sister Venus was beaten 6-1 4-6 6-3 by number one seed Martina Hingis in the second semi-final.

A little luck and a lot of determination lifted Williams to victory in the first Grand Slam semi-final of her young career. She earned the decisive break of the third set with a shanked service return that just made it over the net. Davenport raced up but couldn't scoop it back over.

"After 17 years, I say I deserve a break once in a while," said Williams, who fought off five break points in the next game - despite a couple of double faults - to solidify her advantage.

"I just decided I couldn't lose serve," Williams said. "I just had to hold in, hold my own, hold my serve even if I was down a break point.

"I just told myself, `Serena, stay strong."'

Davenport saved a match point in the ninth game to force Williams to serve for the match.

The youngster betrayed no sign of her inexperience as she gave herself two match points with two service winners up the middle and an ace - her 12th - out wide.

She closed it out with a punishing second serve that Davenport could do nothing with.

"She can serve a lot of serves well," Davenport said. "She has a great serve, one of the better serves in women's tennis, if not the best serve. That's what you have to deal with, get them back, but still be aggressive. It's a hard thing to do."

Venus Williams, however, could not overcome the greater all-round game of world number one Martina Hingis in the second semi-final.

Hingis totally dominated the first set, playing sparkling tennis to win it 6-1. Williams then hit back in the second set, finding her form and not allowing Hingis the time that she had had in the first set. Williams's 6-4 win in the second set was well-deserved and ensured that the third set was going to be tensely fought.

Where Hingis had dominated the first set and Williams the second, the third was the most even as the momentum swung both ways. Eventually it was Hingis who showed the greater composure to book herself a place in the final, winning the decider 63. Rain held up play for more than five hours, forcing organisers to move the men's doubles final off the Arthur Ashe Stadium Court to the smaller Louis Armstrong court.

Meanwhile, Andre Agassi and Yevgeny Kafelnikov square off today in the final before the final in the men's championships in New York.

Their semi-final showdown will be not only for a berth in the championship match, but also for the world number one ranking.

"It's great that you're playing a match at the semis of the Open that has also that riding on it," Agassi said. "I can't honestly say that neither one of us will be thinking about that."

The star wattage in the bottom half of the draw has thrown the second semi-final into stark shadow.

Seventh seed Todd Martin of the United States and unseeded Frenchman Cedric Pioline have emerged from the half of the draw that was expected to produce a repeat of last year's Pete Sampras-Pat Rafter semi-final.