U.S. OPEN : Youth Served; Not Sabatini : Tennis: Capriati, 15, is overpowering in reaching semifinals, 6-3, 7-6 (7-1), while defending champion’s service goes south.

Gabriela Sabatini’s one-year reign as queen of the U.S. Open came to an end Tuesday night, ushered out by a 15-year-old named Jennifer who is just two steps away from the crown.

The Capriati Era?

It looked a lot closer after Sabatini submitted meekly, 6-3, 7-6 (7-1), a strangely humbling experience for the 21-year-old defending champion who was deserted by her trusted ally, the serve.

Now it’s Capriati’s third Grand Slam semifinal, but the first one in which she thinks she can go farther.

“In the beginning, I was a little surprised and happy to be there,” Capriati said. “Now I’ve come close and want to go all the way.”

Capriati made the 1990 French Open semifinals and lost to Steffi Graf. She reached the semifinals at Wimbledon in July and lost to Sabatini, but won’t have that problem again in Friday’s semifinals. Instead, Capriati will play Monica Seles, a 6-1, 6-2 winner over Gigi Fernandez.

First, Capriati had to get past Sabatini, which she managed to do with surprising ease. Witnessed by 19,579 on the Stadium Court, Sabatini helped plot her own demise with 43 unforced errors.

Even more damaging to Sabatini was the breakdown of her serve. She had six double-faults and no aces and won only seven of 24 points on her second serve.

Sabatini, who had 12 double-faults in her previous match, claimed once again that her serve wasn’t all that bad, although it certainly appeared to be.

“It has improved a little bit,” Sabatini said. “Of course, that is something I have to still work on.”

And Capriati can work on closing out matches better. Twice she served for the match--at 5-4 and 6-5--and lost her serve both times.

“I wasn’t nervous,” Capriati insisted. “On my serve, I was just going for it too much. I just wasn’t doing it.”

There were six service breaks in the second set, which was truly destined for a tiebreaker.

Capriati took a 4-0 lead in the tiebreaker on four Sabatini errors in succession, moved to match point on a spinning topspin lob and a stinging cross-court backhand into the corner, then ended it with a short volley angled cross-court and out of sight.

“I wasn’t strong enough mentally to play good when I had to play good,” Sabatini said.

In her attempt to set a land speed record, Seles fell short.

Seles racked up the first set of her quarterfinal match with Fernandez in 18 minutes, but ruined the curve with a 35-minute second set, which made the final count 53 minutes and the score a wipeout.

It was not a pretty sight. Fernandez, a doubles specialist playing her first Grand Slam quarterfinal, splattered 35 unforced errors and lost her serve five times.

“If she had a volley, she would be scary,” Fernandez said.

And if Seles hadn’t skipped Wimbledon, she would be a lot more popular with her peers, said Fernandez, who waited until after the match to fire her best shots.

“I don’t think she is very popular in the locker room, but she never was,” Fernandez said. “This is not a popularity contest.

“Most of the top players don’t hang out. They are not friendly with anybody. They go, play and they leave. So it is hard to be popular when you do that.”

Seles admitted she does not sit around and shoot the breeze with a lot of the other players, but she said she learned how to act after getting the cold shoulder more than once when she was starting out.

“I still have a lot of players who I beat when I was 14 who don’t talk to me because of that reason,” she said. “I say forget it. I am totally normal, but you know, they are not.”

U.S. Open Notes

Jimmy Connors, tied for No. 936 in the rankings at the first of the year, is No. 174 and probably will be between No. 100 and No. 110 at the end of the Open. . . . Connors, who was 39 Monday, is the second oldest U.S. Open quarterfinalist. Ken Rosewall was 39 years 10 months in 1974 and eventually reached the final, where 22-year-old Jimmy Connors beat him. It was the first of Connors’ five U.S. Open titles (1974-76-78-82-83). . . . Connors gets a break and doesn’t have to play Paul Haarhuis until Thursday night. . . . In today’s quarterfinals, unseeded Javier Sanchez plays No. 2 Stefan Edberg, and No. 5 Ivan Lendl plays No. 3 Michael Stich.