There were no big surprises opening the Sovran Bank/D.C. National Classic, what with the top nine seeds not playing yesterday at Rock Creek Tennis Stadium, but that's no consolation to Jaime Yzaga.

Among the seeded players who did compete yesterday, one lost. Unseeded Karel Novacek of Czechoslovakia easily overmatched No. 13 Yzaga of Peru, 6-3, 6-4, as the temperature reached 94 degrees.

"I was winning the whole match, so the heat wasn't as bad for me," said Novacek, 21.

Yesterday's seeded winners included No. 10 Francisco Maciel of Mexico coming back to beat Argentina's Marcelo Ingaramo, 6-7 (7-1), 6-4, 6-2; No. 11 Libor Pimek of Czechoslovakia downing Sweden's Stefan Eriksson, 6-3, 1-6, 6-1; No. 14 Pablo Arraya of Peru breezing past Jonny Levine of Phoenix, 6-4, 6-0; No. 15 Ronald Agenor of France overwhelming West Germany's Hans Schwaier, 6-2, 6-4, and No. 16 Fernando Luna of Spain eliminating Argentina's Roberto Arguello, 6-1, 6-3.

Novacek tormented Yzaga with a sharp backhand and strong serve in the 6-3 first set. Yzaga led, 2-1, in the second when Novacek got him on the run. The Czech stayed on the base line, sending forehands down the line and backhands cross court to hold serve, then broke Yzaga with another pinpoint backhand that left him flat-footed, frustrated and down, 3-2.

Yzaga didn't fall, though, without a comeback bid. Serving for the match at 5-2, 40-15, Novacek, with Yzaga again out of position, whistled a forehand to the corner. It was ruled out. "It wasn't a bad call," Yzaga said.

Said Novacek: " The match was finished. I had him at 5-2 and my forehand was right on the line, but the call was changed. For a few moments I lost concentration, and he got back to 5-4. But I got back to concentrating on my service game, and I went on" to a forehand winner that ended the match.

"I didn't expect to win this match," Novacek said. "I lost in the first round of my last five tournaments. This helps. I think I have a pretty good chance of winning another round. We'll see."

Maciel, who reached the round of 16 at the French Open, has improved his world ranking from No. 70 beginning the year to No. 46 this week. "Before, I was having too much fun with tennis," Maciel said, "but now I'm taking it more seriously. I want to be in the top 10 this year. It's difficult, but not that difficult."

Ingaramo fought off five match points before Maciel finally finished him with an ace and an overhead smash. "I know how to win the big points now," Maciel said.

Arraya, after hurdling Levine, said, "Right now, I'm very confident. I just got back from Davis Cup, where I beat third-seeded Martin Jaite and No. 12 seed Horacio de la Pena. I think I'll do well on the clay here."

Area native Harold Solomon, who won here in 1974, rushed past Norm Schellenger of Midlothian, Va., in night action, 6-3, 6-3.

McLean's Dan Goldie's scheduled match last night against Houston's Richey Reneberg was postponed at the request of Goldie, who strained his right hamstring playing in the U.S. Pro Open in Brookline, Mass., last week. Goldie and Reneberg will play this afternoon's third Stadium Court match.