Fernandez Feels Fine, Beats Sanchez Vicario : U.S. Open: Loss by third-seeded Spaniard and defending women’s champion is tournament’s biggest upset.

It is not the way any athlete wants to be known. Mary Joe Fernandez has, for the last few years, had a reputation as more of a chronically ill or injured player than one who fights her way to victory.

Her fragile health has ebbed and flowed, with no thought of the tournament schedule of women’s professional tennis. Even here at the U.S. Open, having pronounced herself healthy and strong, Fernandez developed a sore hamstring that caused her to drop out of doubles and mixed doubles.

But Sunday night, playing in her own national championships and before a wildly supportive crowd, Fernandez was the master of her body and the defending champion, with a 1-6, 6-4, 6-4 victory over third-seeded Arantxa Sanchez Vicario.

It was the biggest upset in the Open so far--the Spaniard is the highest seeded player to lose on the men’s or women’s side. The fourth-round loss is the earliest exit for any defending women’s champion since Hana Mandlikova lost in the fourth round to Wendy Turnbull in 1986.

Fernandez, seeded 14th, reveled in the triumph, hoping she has shed her image as a talented but hapless player.

“I’m sure it will mean more, down the road, knowing that ‘Hey, I hung in there, came back against a player who is very tough mentally and such a good player,’ ” Fernandez said. “Hopefully it shows that I do have courage. I hung in there.”

Fernandez’s woes have ranged from the minor--stomach flu that caused her to withdraw from the Canadian Open last month--to the serious--a long battle with endometriosis, an illness that causes the uterine lining to shed, resulting in severe cramping and, often, anemia.

The 24-year-old looked determined to battle the tour’s most determined player. Sanchez Vicario has appeared in the final of seven of the last eight Grand Slam events.

Sanchez Vicario broke Fernandez at a crucial juncture in the first set, with Fernandez serving at 1-4. The game, which both players called the turning point of the first set, went to deuce 12 times. Sanchez Vicario had 10 break points and Fernandez had two game points.

Fernandez shook it off and began to attack in the second set. Her serve-and-volley strategy paid off, and Sanchez Vicario, accustomed to being the aggressor, was pinned at the baseline without a backup plan. Fernandez poured it on in the third set and ultimately overwhelmed the defending champion.

“I let her into the match; that was my mistake,” Sanchez Vicario said. “You try to defend [your title]. I don’t have to be disappointed; I played a great match. She played better than I did at the end. There was nothing I could do.”

Fernandez was jubilant for the victory and her good health.

“It’s been great,” she said. “I’ve had a little patch of the stomach flu for a few days, but, knock on wood, I’ve been feeling pretty strong.”

Sanchez Vicario didn’t have the only bad day at the National Tennis Center. It was a bad day for teen-agers on Stadium Court.

Earlier, Pete Sampras defeated 18-year-old Mark Philippoussis, but just barely. Sampras beat the hard-serving Australian to advance to the fourth round, 6-7 (7-5), 7-5, 7-5, 6-3. Sampras called the match, “very, very dangerous.”

Two women’s fourth-round matches featured the two most innocuous servers on the tour and two players with the most lethal forehands. In the first, Gabriela Sabatini defeated 14-year-old Martina Hingis, 6-2, 6-4. In the second, Steffi Graf ended 19-year-old Chanda Rubin’s winning streak, 6-2, 6-2.

Sabatini and Hingis hit their serves at about 60 m.p.h., slow enough to not only read the serve but also the insignia of the ball’s manufacturer.

The Swiss teen-ager committed 41 unforced errors and admitted to being frustrated with her mistakes. She did, however, acknowledge the match’s one inescapable truth: “In certain ways,” Hingis said, “it is a little crazy to be out there at 14 years old.”

Rubin was expected to give Graf a harder time, but the American’s serve deserted her at key moments. Rubin had seven double faults in the match. She also chose to challenge Graf’s power with her own--each player uses a huge forehand as her main weapon. Going for big shots caused Rubin to make 31 unforced errors.

U.S. Open Notes

Thomas Muster getting in a lather is not unusual. Neither is Muster telling U.S. Open officials they are stupid, which he did Sunday.

That was the scenario when Muster was assigned Court 16 to play Francisco Clavet in a third-round match. Muster won, 0-6, 6-4, 6-3, 7-5, then complained that the court--considered the third-best at the National Tennis Center--was an inappropriate place for a player of his stature.

“I just think it is ridiculous they put the No. 3 player in the world out on Court 16,” Muster said. “I think it is pretty stupid to schedule it like that. I had a little discussion yesterday with the referee--it is just because some players are American that they are playing on the Stadium Court and the Grandstand, which I think is a little bit respectless. For years they are telling me I was not good enough to play on those courts; now I am No. 3 in the world, and they still put me in the garbage out there.”