FLUSHING, New York (Ticker) -- Seventh seed Serena Williams of the United States, the "other sister" throughout her career, proclaimed herself a star in her own right today as she upset top seed Martina Hingis of Switzerland, 6-3, 7-6 (7-4), to win the U.S. Open.

Competing in her first Grand Slam final, the 17-year-old Williams, who has played in the shadow of her 19-year-old sister Venus, pulled off what Venus has not been able to do, beat Hingis in a Grand Slam tournament and win a major title. Her victory over Hingis came one day after the Swiss teenager rallied in the third set to defeat Venus in the semifinals.

"I've been practicing so long for this and now it's here," Williams said. "It's hard to believe. I've been working for the U.S. Open since Wimbledon when I wasn't able to play. I was able to take advantage of my opportunity. You don't get opportunities often and you have to take advantage."

Williams joins Althea Gibson as the only black women to win a Grand Slam title and is the first black since Arthur Ashe won Wimbledon in 1975 to win a Grand Slam event. She became the lowest seeded female in the Open Era (since 1968) to win the U.S. Open and collected $750,000 for the victory.

On the men's side, second seed Andre Agassi outslugged and outworked Yevgeny Kafelnikov of Russia, 1-6, 6-3, 6-3, 6-3, in a baseline duel today to set up an all-American final Sunday against seventh seed Todd Martin.

With the victory, Agassi also will assume the No. 1 ranking in men's tennis from fellow American Pete Sampras, who had to withdraw from the tournament due to a disc problem in his back. Kafelnikov, the third seed, could have grabbed the top spot in the ATP rankings by beating Agassi.

Showing no ill effects from the stomach problems he had just a few days ago, Martin blew past unseeded Cedric Pioline of France, 6-4, 6-1, 6-2, in just 96 minutes earlier today to advance to his second career Grand Slam final.

Williams was in control of the match through nearly two full sets until Hingis mounted a charge to force a second-set tiebreak after fighting off two match points serving at 3-5.

Hingis held on for 4-5, broke for 5-5 and held again for a 6-5 lead. She actually managed a set point with Williams serving at 5-6 but Williams held on in a dramatic exchange of shots to send the set to a tiebreak.

Williams took a 4-2 lead in the tiebreak but Hingis fought back once again to tie it at 4-4. It was all Williams after that as she summoned back her fading strength and nailed a forehand service return winner for a 5-4 lead. Williams reached match point when a lob by Hingis floated just over the end line and she won it on the next point when Hingis sent a backhand just past the baseline.

"I took a lot of time serving for the match," Serena Williams said. "I feel I can't be beaten in a tiebreak. I just have a lot of confidence. Tiebreaks depend on the serve a lot and I feel I have a big advantage with my serve. When the ball went long (at match point), I didn't know whether to laugh or scream or cry. I think I did all of them."

Early on, Williams used her superior size and strength to overpower Hingis, especially in key situations. After holding off two break points in the first game of the match, Williams broke for a 2-0 lead.

Hingis had break opportunities in every game but managed only one to put the set back on serve at 4-3. But Williams broke back immediately for a 5-3 lead. Hingis had two more break chances with Williams serving for the set but the American teenager would not fold and put away the set by ripping a backhand up the line to take the set.

Williams' go-for-broke style produced 19 winners and 25 unforced errors in the opening set. Hingis managed only one winner and made five unforced errors and won 25 of her 34 points in the set on Williams' errors. Hingis converted only one of seven break-point opportunities in the opening set.

For the match, Williams had 36 winners and 57 unforced errors, with several of her key shots coming off Hingis' serve. She also had eight aces and three double faults.

Hingis, who seemed listless and confused until her late burst, managed only seven winners and made an uncharacteristic 24 unforced errors, including the last two that cost her the tiebreak and the match.

"I had my chances and I didn't take them," said Hingis. "She pulled it out better today. She was always leading. I felt I was always behind, always had to be defensive. She was just better today -- after yesterday."

Hingis admitted the duel with Venus Williams on Friday left her drained for the match with Serena.

"It was hard to move, but it was the same for the both of us," said Hingis. "She also had a three-setter (in the semifinals). She actually had a harder tournament, too. She played more than I did. She also played doubles.

"I had a hard time falling asleep, but that's no excuse. You have to go out there and play. It's a tough schedule, playing the toughest matches at the end of the tournament like one after the other. I love CBS changing their request there (to play Friday and Saturday). You just have to deal with it."

Hingis also countered a claim by Richard Williams, the father of the Williams sisters, that she was "scared out there".

"I wasn't scared. I just couldn't play my game," she said. "I missed terrible things. She did, too. I think I wasn't the only person at the end who was scared. She had two match points, wasn't able to close them out right away. I think she was a bit more scared than I was actually at the end because I've been there, done it. For her, it was the first time in the finals. She's a great competitor, a great fighter. It paid off for her today. Hopefully, next time I'm going to have a better chance. We are both going to be more relaxed, fresh, going into those matches."

The victory by Williams assures that there will be two American-born singles champions at the U.S. Open for the first time since 1982, when Jimmy Connors and Chris Evert won titles.

There had been some words exchanged over the two weeks between Hingis and the Williams family but Serena said Hingis was quite complimentary when it was over.

"She told me that it was a great match and how exciting it was," Williams said. "There was no bitterness there, like you might expect from some people in that situation. She's really a sweet person. I'm glad I was playing her in the final."

Venus and Serena Williams remain alive in women's doubles. They have reached the semifinals and will face the team of Mary Pierce of France and Barbard Schett of Austria tonight. The Williams sisters are seeded fifth, and Pierce and Schett are the 12th-seeded team. The winner will face the unseeded duo of American Chanda Rubin and Sandrine Testud of France in Sunday's final.

Kafelnikov took advantage of Agassi's errors to take the opening set in just 22 minutes and appeared to be in complete control. But Agassi pulled himself together in the second set. He broke to go up, 3-1, and broke again in the final game to even the match.

Agassi continued to apply the pressure in the third set and Kafelnikov's game slowly began to fall apart. Agassi broke in the opening game and again in the fifth for a 4-1 lead.

Kafelnikov managed to break back to 4-2 but Agassi continued his assault from the baseline. With Kafelnikov serving at 3-5 and deuce, Agassi fired a spectacular forehand passing shot up the line and a wicked backhand passing shot up the other side to set up set point. Agassi broke to take the third set when Kafelnikov drilled a backhand into the net.

Kafelnikov's pace was obviously slowing in the fourth set and Agassi forced the critical break in the sixth game. Kafelnikov double-faulted to set up break point at 15-40 and then put a backhand into the net to hand Agassi a 4-2 lead.

After managing to fight off a match point serving at 5-2, Kafelnikov had one last chance to get back into the match with two break points at 15-40 as Agassi served for the match.

But Agassi stormed back to deuce and won it on his third match point as he drilled a shot deep into the corner and Kafelnikov hit an off-balance forehand into the net.

Agassi had 33 winners and 40 unforced errors while Kafelnikov hit 34 winners and committed 49 unforced errors in the two hour, 12-minute match.

"I was really trying to dictate play. I just kept missing," said Agassi of his dismal performance in the first set. "I was fortunate to get an early break in the second set and that got me into the match. I recovered a little bit, started moving my feet and got into a rhythm. It's great to have a couple of Americans back in the final here."

It will be the fifth all-American U.S. Open final in the Open Era (since 1968), and the first since Sampras beat Michael Chang in 1996.

Kafelnikov admitted that his game began to suffer after the opening set.

"I was quite successful in the first set," Kafelnikov said. "But then Andre started to move better and place the ball better. In the second set, I thought he'd start to go for his shots. That's what he did and he started playing extremely well. I felt like I was a half step behind all the time. He was putting so much pressure on me that I was trying to recover just to get to the ball."

Kafelnikov was attempting to reach his third career Grand Slam final, having won this year's Australian Open and the 1996 French Open. This was his first U.S. Open semifinal appearance.

Agassi will be appearing in his third straight Grand Slam final and will seek his second Grand Slam title of the year and fifth of his career. He became only the fifth male to win all four Grand Slam tournaments by winning the French Open. Agassi also reached the Wimbledon final, where he was beaten by Sampras.

This will be Agassi's fourth appearance in a U.S. Open final. He won the title in 1994 and was runner-up in 1990 and 1995.

Today's victory was Agassi's 34th in his last 38 matches, with three of the losses coming against Sampras. Kafelnikov is the only other player to defeat Agassi during his hot streak.

Martin simply overpowered Pioline, serving 14 aces and having his serve broken only once. He survived four break points in the opening game, broke for a 5-3 lead and served for the set.

Pioline broke right back, but it was his only shining moment as Martin broke right back to take the set and steamrolled the rest of the way. Martin broke twice in succession in the second set to build a 5-1 advantage and took a commanding two-set lead when Pioline netted a backhand on set point.

The third set was much of the same. Martin broke at love for a 2-1 lead and applied the crusher with a break in the seventh game for a 5-2 advantage. He closed out the game with a running crosscourt backhand volley and served out the final game at love, firing his 14th ace to set up match point and closing it out when Pioline netted a forehand.

Martin had 30 winners and 21 unforced errors while Pioline managed 22 winners to go along with 31 unforced errors.

"I squeaked through a tough first game," Martin said. "Then I found a rhythm and he lost his. I think he got frustrated with the conditions. It was pretty windy. In fact, I played pretty conservatively. He wound up making a lot of errors."

Martin pointed to his serve as a key in the victory.

"Usually, I rely on my serve a lot," he said. "Today, it got me out of a few jams. The 14 aces can come in four games. You need to spread them out and I did a good job at that today."

Martin feels he is better prepared for his second Grand Slam final. He lost to Sampras in straight sets in the 1994 Australian Open final.

"I have a better perspective," he said. "I think I know why I am playing well, better than I did four or five years ago when I first started to do well. I'm not as good an athlete as I was a few years ago. I rely on a few other attributes."

Martin had struggled to reach the semifinals before breezing to victory today. He blew a two-sets-to-none lead in the opening round and needed to win a fifth-set tiebreak to defeat qualifier Stephane Huet of France.

The American also had to rally after losing the first two sets to defeat ninth seed Greg Rusedski of Britain in the fourth round. Martin trailed, 1-4, in the fifth set before winning the last five games. He needed two liters of intravenous rehydration after that match to combat exhaustion, dehydration and the effects of a stomach virus.

Pioline said Martin simply was too good for him today.

"I think he just played too good. He was reading the ball very well today, catching everything," Pioline said. "He made very few unforced errors, he was serving big. He was playing much better than me today. I played a couple of times against Todd. I think it's the first time he's playing that way. I've never seen him playing like this. If he's able to play that way tomorrow, I think he has a good chance."

Pioline was attempting to reach his third Grand Slam final. The 30-year-old Frenchman made the U.S. Open final in 1993 and the Wimbledon final in 1997, losing to Sampras in straight sets both times.