NEW YORK, SEPT. 6 -- He is the second seed in this tournament and yet was referred to in the U.S. Open program as a dark horse. At 21, he has two Grand Slam titles, but no one compares him to Boris Becker.

Today, Stefan Edberg did what he almost always does: He won a tennis match and made it look easy, so easy that, as he played, the Stadium Court was almost empty. Where were the spectators? Packed into the grandstand to watch a doubles mismatch: Martina Navratilova-Pam Shriver pounding Chris Evert-Gigi Fernandez, 6-0, 6-1.

Edberg won almost as convincingly, crushing Kelly Evernden, 6-2, 6-1, 6-4, to reach the round of 16 on an overcast afternoon when form held once again and the buzzing around the grounds was more the result of John McEnroe's fines than the tennis.

There were some near upsets on the outside courts in the women's matches. Zina Garrison, the seventh seed, survived two tie breakers to beat Katerina Maleeva, 7-6 (7-4), 7-6 (10-8). Her doubles partner, good friend and fourth-round opponent, Lori McNeil, had even more trouble with Nicole Provis, finally beating her, 5-7, 6-1, 7-6 (7-2).

Both these matches were examples of young veterans -- McNeil and Garrison will both be 24 before the end of the year -- beating rapidly improving teen-agers. If the seedings for the Open had been done a week later, Maleeva, who is 18, would have been seeded. She is now ranked 16th in the world, six places below her 20-year-old sister Manuela, who also survived a three-setter with a teen-ager today, beating 16-year-old Mary Joe Fernandez, 6-2, 0-6, 6-3.

Provis is 17, perhaps the next Australian star. She recently cracked the top 100 and today gave McNeil trouble throughout. Provis is 5 feet 9 and weighs 140 pounds and, like McNeil, she attacks constantly. Points were usually decided by who got to the net first.

While the seeds struggled outside, they breezed on the show courts. Steffi Graf, the top seed, needed just 38 minutes to beat Patricia Tarabini, 6-2, 6-0. Chris Evert (No. 3), who has dropped four games in three matches, took a little longer -- 64 minutes -- to beat Natalia Zvereva, a 16-year-old Soviet, 6-0, 6-2. And Pam Shriver took exactly 43 minutes to manhandle Laura Golarsa, 6-1, 6-2.

In all, 14 of the 16 seeded women reached the fourth round, the same number as last year.

The men's draw has not exactly been full of upsets, either. All eight seeded men in the top half of the draw reached the round of 16. In the bottom half, however, three unseeded players made the fourth round along with Edberg, No. 3 Mats Wilander, who blasted Libor Pimek, 6-2, 6-0, 6-1, and No. 5 Miloslav Mecir, who survived two rain delays and his erratic play to beat Jakob Hlasek, 6-4, 6-4, 2-6, 6-4.

Ken Flach leads No. 14 Emilio Sanchez, 4-3, in a match suspended by rain.

Ramesh Krishnan, the graceful Indian who beat Joakim Nystrom on Friday, played impeccably to wipe out Johan Kriek in three sets. Mark Woodforde, the qualifier who beat Tim Mayotte, embarrassed Milan Srejber, a quarterfinalist last year, dropping only four games in three sets. And Andrei Chesnokov, who reached the fourth round last year, won easily over Diego Perez.

The favorite to reach the final out of this group is Edberg. He is a better fast court player than Wilander and has had better luck than the other Swedes against Mecir, last year's losing finalist.

"I'm playing very good tennis right now; everything is working quite well," Edberg said. "Today was the easiest match I've had so far, but I'm playing about as well as I can."

Edberg's claim to fame on the tour, other than his classic serve-and-volley game, is a knack for sounding as if he doesn't care after a loss. Last year at Wimbledon, after losing to Mecir, he shrugged it off by saying there was another tournament next week. This year, after dropping a tough semifinal to Ivan Lendl, he quickly pointed out that he was still alive in the doubles.

"It sounds like he doesn't care, but actually he cares so much he isn't even thinking straight after a loss," said his agent, Tom Ross. "The guy is very intense, easily the most intense of the Swedes."

Edberg shrugs off his reputation. "If people think I'm boring, there's not much I can do," he said today. "All I can do is try to play good tennis . . . I joke around and have a good time. But when I'm playing tennis, I play tennis."

He won his second straight Australian Open in January, beating Pat Cash in five sets. He has the best record on the tour this year, but his loss to Lendl at Wimbledon was a surprise because grass is Edberg's best surface. TODAY'S FEATURED MATCHES

Stadium Court -- Ivan Lendl (1), Czechoslovakia, vs. Anders Jarryd (16), Sweden; Jimmy Connors (6), Sanibel Harbour, Fla., vs. Henri Leconte (11), France; John McEnroe (8), Cove Neck, N.Y., vs. Andres Gomez (9), Ecuador; Pam Shriver (5), Lutherville, Md., vs. Jana Novotna, Czechoslovakia.

Grandstand -- Steffi Graf (1), West Germany, vs. Sylvia Hanika (13), West Germany; Martina Navratilova (2), Fort Worth, vs. Catarina Lindqvist (14), Sweden; Chris Evert (3), Fort Lauderdale, Fla., vs. Manuela Maleeva (10), Bulgaria; Boris Becker (4), West Germany, vs. Brad Gilbert (13), Piedmont, Calif.

Court 16 -- Hana Mandlikova (4), Czechoslovakia, vs. Claudia Kohde-Kilsch (9), West Germany; Gabriela Sabatini (8), Argentina, vs. Bettina Bunge (12), West Germany.