Stanislov Birner's good thing finally came to an end yesterday.

The quiet, resolute Czechoslovakian couldn't summon enough energy in his eighth match of the week to deal with the impeccable base-line game of third-seeded Jose-Luis Clerc, who advanced to tonight's 7:45 Washington Star International championship with a straight-set victory.

Clerc's 6-1, 6-3 triumph on the stadium court enabled the 22-year-old Argentine to move into the Star final for the second straight year. Clerc, ranked No. 5 in the world, has not lost a set in his five matches.

In the second semifinal, which took more than four hours because of two rain delays, Guillermo Vilas, the fourth seed and three-time Star champion, advanced to the final by defeating powerful, young Andres Gomez of Ecuador, 6-4, 3-6, 6-3.

It was Vilas' 23rd straight victory at the Star. His only loss in the last seven years over 28 matches was in 1974 to Harold Solomon in the final.

Both finalists are from Argentina. Vilas won in 1975, 1977 and 1979. Clerc lost a three-set final to Brian Gottfried in last year's championshio. Neither faced a seeded player in reaching the final.

As affable and polite as Clerc is, he was somthing of a villain yesterday in routing Birner, a small, awkward scrapper who had become a darling of the crowd this week.

Ranked No 153 in the world, Birner had to win three matches in the preliminary qualifying rounds last weekend, including two in one day, to make the main draw. He then defeated No. 2 seed Gene Mayer, 14th-seeded Terry Moor and No. 12 Mel Purcell in the quarterfinal to reach the semifinal round against Clerc.

"This is still the best week of tennis in my life," Birner said. "The (Czech) ambassador called to congratulate me on my matches." day came early in the second set. With Clerc leading, 1-0, Birner had a service winner taken away at 30-30 because Clerc wasn't ready to receive. Many in the 5,800-seat-stadium, two-thirds filled, began to boo.

Birner won the point anyway and was serving to even the set at one game apiece. He served what appeared to be an ace but the ball was called out. "Second serve, Mr. Birner," the umpire said, the crowd showing its unhappiness again. When Clerc walked over and circled the area where he said the ball landed on the line, the umpire said, "Serve two."

But Clerc instead conceded the game to Birner, tying the set, 1-1. "The ball was on the line," Clerc said. "I saw it clearly. I had to say so, especially since it was an ace."

Birner broke serve to move ahead, 2-1, then took a 30-love lead in the next game and seemed on his way to another three-set comeback. But he double-faulted the next point, watched a Clerc backhand winner sail across court then made two unforced errors to lose the game.

Clerc overpowered Birner the rest of the set, angling forehands and coming to net more than usual.

With the second set tied, 2-2, Clerc held serve for a 3-2 lead and ran his margain to 5-2 before Birner won another game. Leading, 5-3, 40-love, Clerc forced Birner deep to his backhand side, then punched the weak return into the open court to close the match.

"I wasn't nervous," Birner said. "I was just too tired. I tried to go to the net after the first set, but I was too tired. Very, very tired. I've never played eight matches in one week before. And Jose was playing very well today. I wasn't steady," he continued. "I couldn't hit 20 straight over the net."

Birner was so unaccustomed to winning that, at his first press conference here, he wanted to stay longer and talk about his victory. "Is that all? Don't you have more questions?" he said.

The second and longest rain delay in the night match came in the second set, with Vilas serving at 2-5, 30-30. Vilas held service, but Gomez held serve at love to take the second set, 6-3.

But Gomez's game, largely dependent on jetlike forehand ground stokes and surprise rushes to the net, suffered in the layoff. The 6-foot-5 Ecuadoran is erratic, anyway, and the delay seemed to hurt him more than Vilas.

"I was serving well after the long delay," Gomez said, "but my game wasn't in the groove." Vilas adjusted by hitting to Gomez's weaker shot -- his backhand -- and making some rare appearances at the net. Vilas took a 4-1 lead and took advantage of errors by Gomez to move to 5-2.

Vilas held at love to take the second set and move into his fifth Star final in eight years.