With the temperature topping 100 degrees on the court, it was perfect weather for a couple of Argentine greats, Guillermo Vilas and Jose-Luis Clerc, and even better for another countryman, little-known Marcelo Ingaramo.

Vilas advanced to the quarterfinals of the D.C. National Bank Classic yesterday with a 7-6 (8-6), 6-3 victory over sixth-seeded Clerc, his longtime rival. They met on a clay court at Rock Creek Tennis Stadium that burned less in anticipation of their first tournament meeting in three years than it did from a merciless sun.

The heat was an affront even to Vilas, who had said earlier this week that the weather suited him because it reminded him of home.

"It was a question of survival," said Vilas, a three-time winner who is unseeded for the first time in seven appearances in the tournament. "I was just trying to get my breath back between points."

It didn't bother Ingaramo, however. A 22-year-old from Buenos Aires who is ranked 122nd in the world, Ingaramo upset fourth-seeded Miloslav Mecir of Czechoslovakia, 6-2, 2-6, 6-2. He, too, advances to the quarterfinals, where he will meet Vilas. Ingaramo is the only other Argentine besides Clerc to have beaten Vilas.

Also advancing to the quarterfinals was Peru's Pablo Arraya, who knocked off his second seeded player in three days with a 4-6, 6-2, 6-4 victory over 15th-seeded Mark Dickson. Third-seeded Yannick Noah of France advanced with a 6-2, 7-5 victory over John Ross, an amateur who plays for Southern Methodist.

Fifth-seeded Aaron Krickstein defeated hard-hitting Thomas Muster of Austria, 6-1, 7-5, to set up a meeting with Noah this afternoon. Noah has won the two times he has played Krickstein.

Martin Jaite, a 20-year-old former ball boy for Clerc and Vilas who is seeded 11th, became the third Argentine to make the quarterfinals with a thorough, 6-3, 6-1 victory over eighth-seeded Libor Pimek of Czechoslovakia.

Pimek was the fourth seed to lose yesterday. Only four remain: Connors, Noah, Krickstein and Jaite.

Clerc and Vilas have had a long rivalry, much of it played out here. They have dominated the D.C. Classic over the last 10 years, Vilas winning three times and Clerc twice.

Yesterday, Vilas wore down his frailer opponent. Clerc claimed the heat didn't affect him, but admitted he became dizzy in the second set. He could not put away Vilas despite leads of 5-3 in the first set and 3-0 in the second. And, just as he took his 3-0 lead, his game came undone.

This was after Clerc had erased four straight set points in the first set tie breaker, coming back from 2-6 to 6-all before Vilas put him away. Clerc saved the four points when Vilas netted a drop shot, put a forehand passing shot in the net, sent a backhand slice wide and netted a weak return of a great serve.

Vilas regrouped, regaining a set point when Clerc's topspin forehand went long, and took the set when Clerc's forehand approach shot went into the net.

Clerc had his chances. He broke serve in the second game of the second set and held routinely for his three-game advantage.

"Then I was thinking I was going to lose," Vilas said. "I had to wake up. After that I played tougher, deeper."

Clerc lost eight straight points over the next two games, seven on backhand errors, as Vilas held serve and then broke at love with a backhand smash to get to 3-2.

Clerc fought back with three break points in the next game, but Vilas held with a backhand pass to even it up. He got his second break in the next game, as Clerc did not put in a single first serve, to go up, 4-3.

Vilas held and then broke for the match. With Clerc serving at 40-30, he hit a gorgeous, twisting backhand volley down the line for deuce. A forehand passing shot down the line gave him the advantage.

At match point, Vilas popped up a weak backhand return off a big serve that fell just over the net, and Clerc had an automatic cross court putaway. But his forehand swing went awry and the ball flew two feet outside the line.

"I played the whole match terribly," Clerc said. "My game is the worst right now. My concentration was zero. I put the forehand in the crowd, and I'm saying 'What's happening?' "

On an outer court, Ingaramo was pulling off a coup against Mecir, ranked 11th in the world. He dominated the first set, buckled under to fatigue in the second, but revived in the third with an attacking game.

"He tried to play very high," said Ingaramo, who reached the quarterfinals for the fourth time this year. "He gave me a lot of topspin. Whenever he gave me an opportunity, I tried to chase the ball to the net."

Perhaps the best-kept secret of the day was the match between Dickson, a stolid, quirky player, and showy Arraya.

Thursday, Arraya knocked off No. 2-seeded Andres Gomez. Yesterday, he was threatened only by his own antics, which ranged from mimicking Dickson to filing a formal complaint for what he called distracting tactics. Arraya strutted, fretted, waggled his hips and took a 4-1 lead in the first set, only to have Dickson break back twice and win the set.

Arraya settled down to win the last sets with something approaching ease. He broke in the first and third games of the second set for a 5-2 lead, and served out the set to even the match.

"I got cocky, I was trying to toy with him, which was stupid, and all of a sudden I was losing," Arraya said. "That was the whole turning point. I just shut up and started playing."