For 2 hours and 45 minutes last night, Jaime Fillol and John Alexander put on a tennis performance that couldn't have been staged much better. Just when it seemed the plot was decided, they would have the audience at Rock Creek Tennis Stadium guessing again.

In a match that came down to a tie breaker in the third set, Fillol finally emerged the winner after surviving two match points moments earlier. He won, 6-7 (8-6), 6-3, 7-6 (7-5), in the first round of the Prudential-Bache Grand Champions tournament.

"No matter how much you think you have it won, anything can happen," said Fillol, 40, who is the captain of Chile's Davis Cup team.

Fillol had the evidence to back that statement last night, taking a 5-2 lead in the first-set tie breaker, only to lose it, 8-6. In the third set, however, it was Fillol who came back.

Twice when Alexander had match point with Fillol serving at 5-6, Fillol held on. At 30-40, he hit a backhand winner. Moments later Alexander had the advantage, but missed wide with a backhand.

"The previous passing shot I hit into the net," Fillol said of the first match point. "The next shot, I said I was going to hit through the ball."

In the third-set tie breaker, Alexander won two consecutive points to tie it, 5-5. But Fillol won the last two points with finesse, tapping in a forehand winner at the net and lobbing to Alexander's backhand. Alexander watched as the ball bounced well inside the base line.

"I was reasonably happy with my play," said Alexander, 35, who played on the Australian Davis Cup team a record 13 years. "I don't think I blew any shots. When he was down, he played his best tennis. There were quite a few times he caught me off-balance."

"John seemed more in command; he was putting on pressure," said Fillol. "I was able to come up with the serve when I needed it."

In other round-robin singles matches last night, Manuel Orantes, 37, of Spain defeated Andrew Pattison, 37, of Scottsdale, Ariz., 6-2, 6-2; Dick Stockton, 35, of Dallas won, 6-0, 6-4, over Ray Moore, 39, of Rancho Mirage, Calif., and Steve Krulevitz, 35, of Baltimore defeated Cliff Richey, 39, of San Angelo, Tex., 6-3, 6-2. In doubles, Pattison and Moore beat Alexander and Ross Case, 35, of Newport Beach, Calif., 6-3, 7-6 (7-3). Friday's matches

Stadium Court at 6 p.m.: Sherwood Stewart vs. John Alexander, followed by Stan Smith vs. Ray Moore, Dick Stockton-Stewart vs. Steve Krulevitz-Cliff Richey.

A2 Court at 6 p.m.: Ross Case vs. Richey, followed by Colin Dibley vs. Andrew Pattison, Jaime Fillol-Dibley vs. Pattison-Moore.