NEW YORK, SEPT. 4 -- Once upon a time, two countries ruled the game of tennis, the United States and Australia. Matches between Americans and Aussies were special, usually because something important was on the line: a Davis Cup challenge round, a Grand Slam title.

Those days are long gone. Even though Pat Cash is the Wimbledon champion, Europeans dominate tennis now. But today, in a far corner of the National Tennis Center, the clock turned back as two dramatic American-Aussie matches unfolded almost simultaneously at the U.S. Open.

Each country won a match, and in both cases the winner was a surprise. The mild upsets involved two players who had to qualify to get into the main draw. That made the matches all the more important to them and they played that way. When it was over, Ken Flach, a man known for his doubles heroics, had saved six match points and had beaten Australia's Darren Cahill, 1-6, 6-4, 3-6, 6-1, 7-6 (17-15). Cahill has recently popped into the top 100 on the computer (91) while Flach is No. 187. That made Flach's escape unexpected.

But the real stunner took place a few yards away, on Court 16, and ended with the exit of American Tim Mayotte, the No. 12 seed. As has been his pattern all summer, Mayotte found himself in a tight match and simply couldn't find the big shots when he had to. He lost to Mark Woodforde, a freckle-faced, red-headed left-hander, 7-6 (7-2), 7-6 (7-5), 3-6, 2-6, 7-6 (7-5).

Those two matches highlighted an active fourth day, one that finally produced some upsets. Mayotte's was the most significant. India's Ramesh Krishnan took out No. 10 Joakim Nystrom, 6-4, 7-5, 6-2. That outcome was hardly shocking since Krishnan did the same thing to Nystrom a year ago at Wimbledon.

And 16th-seeded Wendy Turnbull's loss to Jana Novotna of Czechoslovakia, 6-2, 6-4, surprised almost no one. Turnbull is 34 and fading, albeit slowly. Novotna is 19 and rising rapidly.

The only other seed who had any trouble was No. 2 Stefan Edberg. Playing at night against Dan Goldie, the 1986 NCAA champion from McLean, Edberg played a loose tie breaker in the first set and had to play very solid tennis to finally wear down Goldie, 6-7 (7-4), 6-4, 6-2, 6-4.

Goldie pushed him right to the finish, coming from 4-0 down in the tie breaker to take the opening set.

But Edberg didn't flinch. He began to find the corners with his passing shots and Goldie's only service break in the match came with Edberg two breaks up in the third set.

"He played very well," Edberg said. "Last year when I played him here {in the round of 16} he seemed a little nervous. Tonight, he played much better."

The rest of the seeds advanced with ease. On the men's side, Mats Wilander (No. 3), Miloslav Mecir (No. 5) and Emilio Sanchez (No. 14) won in straight sets. The only man to upset a seed before today, Peter Lundgren, lost. Lundgren, who beat Pat Cash two nights ago, lost to Soviet Andrei Chesnokov, 3-6, 6-2, 7-5, 2-6, 6-0.

Among the women, Chris Evert, Pam Shriver, Manuela Maleeva, Lori McNeil and Sylvia Hanika all moved into the third round without incident, as did Mary Joe Fernandez, the just-turned 16-year-old who beat the top Soviet woman, Larissa Savchenko, 6-1, 6-4. Shrivers's victim was Iwona Kuczynska, who defected from Poland in 1981. Kuczynska made it through qualifying to become the first Polish woman in the main draw here since 1938.

Although Evert has not -- contrary to rumors -- been playing here since 1938, she did reach two more milestones today, winning the 1,200th match of her career and her 100th at the U.S. Open. She beat Niege Dias, 6-0, 6-1, the same score by which she won her first Open match 16 years ago.

For Evert making the semifinals at this tournament is a breeze -- she has never failed to get that far. By contrast, nothing is easy for Mayotte here. He has never been beyond the round of 16 and today marked the end of his disappointing summer.

His loss marked the fourth time this summer that he has not been able to get out of a fifth set. He had lost in five sets to Mikael Pernfors at Wimbledon and in five sets twice during the Davis Cup loss to West Germany in July.

"It comes down to me, what I'm doing or, actually, what I'm not doing," Mayotte said. "I'm an aggressive player. I have to be the one to use my weapons to win the match. Lately, I've been hedging when I needed to be attacking."

That was never more true than today. Two sets down, Mayotte climbed back to even the match. Down a break in the fifth, he broke back. Finally, when Woodforde double-faulted in the tie breaker, he led, 3-2, and seemed to be in command. On the next point, he double faulted, his second serve hitting the bottom of the net. "When I saw that, I knew he was very nervous," Woodforde said. "It helped me a lot."

Woodforde went into the match feeling a lot more confident than a player ranked 134th in the world should feel facing No. 14.

Woodforde wanted to serve to Mayotte's often-inconsistent backhand and attack Mayotte's second serve if he had the chance. He had plenty of chances because Mayotte served only 58 percent for the match.

Woodforde came out blasting, breaking Mayotte at love to start the match. Mayotte broke back to get to 5-all, but looked thoroughly confused in the first tie breaker.

He lost another tie breaker in the second set -- throwing in a telltale double fault -- and could have been out of the match quickly. But with Woodforde serving at 3-4 in the third, chair umpire Rudy Berger overruled what would have been a game-ending ace. Woodforde argued at length, lost the argument and then the game. He promptly unraveled, double-faulting four times to begin the fourth set. Suddenly, the match was even.

By the fifth set, the Court 16 grandstand was packed and Woodforde had his second wind, breaking to lead 3-1. But Mayotte played a superb game, nailing two forehand returns to break back and on they went to the tie breaker. "I hear people yelling, 'Just get him to the breaker, Tim,' " Woodforde said. "That was fine with me. I'd already won two of them."

Then, he made it three. Mayotte certainly had chances. Woodforde's double fault made it 3-2, Mayotte, with two serves to come. But Mayotte's double fault changed the tone of the match. Woodforde promptly came up with a topspin lob to go up, 4-3. He got to match point at 6-4 with a chip backhand winner. Mayotte saved one with an ace to make it 6-5.

But he couldn't save the second match point and quietly headed for home with 1-6 record in five-set matches this year and a 1-4 record in five-setters here.

His mood was exactly the opposite of Flach, who looked helpless early and then hung on through an excruciating tie breaker.

Flach finally won it on his sixth match point with a sharp forehand volley. He reacted as if he had won the Open, screaming and throwing his arms in the air. A few minutes later, reality set in.

"Oh God," he said. "I can't believe that I gotta go play doubles now." He survived that one too, coming back with partner Robert Seguso to beat the tough French team of Guy Forget and Henri Leconte, 5-7, 6-3, 6-4.