John McEnroe and Ivan Lendl each made great escapes from three-set matches today to advance, as expected, to Sunday's final of the Tournament of Champions at the West Side Tennis Club in Forest Hills.

First-seeded McEnroe ousted Henrik Sundstrom, 6-2, 3-6, 6-2. Lendl, the second seed, did the same to teen-ager Aaron Krickstein, 6-1, 2-6, 6-1, at the tennis club that housed the U.S. Open until 1977.

The winners played mostly brilliant tennis, promising perhaps great things for their confrontation at 12:15 p.m. Sunday in the tournament they are using as a warmup for the French Open.

McEnroe had looked listless in his quarterfinal victory Friday over Claudio Panatta and set out today expressly to improve on that performance. Although McEnroe still had trouble with his first serve, getting in only 44 percent, everything else was in smooth working order.

"I didn't play well yesterday, that was the whole idea," McEnroe said. "I told myself I couldn't afford to do that against a dangerous player. And today I had a little motivation."

Sundstrom and McEnroe had met just once before, in the 1984 Davis Cup final on clay. Sundstrom prevailed that time in helping Sweden win the Cup in an upset. McEnroe got a measure of vindication today.

"I was glad to be able to beat him on clay," he said. "But I feel bad that I had to beat him in this match instead of that one."

It was hard to believe Sundstrom ever had beaten him as McEnroe produced drop shots and delicate volleys of every shape and form. McEnroe broke him in the fourth game of the third set for a 3-1 lead, then again for the match in five points.

After a textbook first set in which McEnroe broke serve in the fifth and seventh games, the second set was a combination of his carelessness and great serving by Sundstrom, who had eight aces in the match.

Sundstrom broke serve in the eighth game, when McEnroe put two drop shots in the net and missed an overhead. Sundstrom finished him off with a backhand passing shot that traveled cross court at the speed of light, then held serve in the next game with an ace to win the set.

"That great backhand passing shot gave me a lot of confidence," Sundstrom said. "But I gave away that break early in the third set, maybe the same way he gave his away in the second. I thought I was playing better, but he broke me quick."

Krickstein and Lendl had never met in a Grand Prix event, and Lendl, loking imposing, took full advantage. Krickstein started and finished tentatively, hitting his two-handed backhand shallow and his large forehand in the net or long.

Lendl crossed him up with lobs and drop shots, put some extra force in overheads and generally intimidated his soft-spoken opponent. Lendl broke serve in the fourth and sixth games of the final set and held at love in three of his four serving games.

Krickstein was broken five times, three times in the first set. He committed 32 unforced errors, 13 each in the first and third sets.

Although Krickstein, 17, is a clay-court specialist, he has a wide variety of shots to go with his considerable base line game. In the second set, his high swinging forehand and some smart thinking threw off Lendl.

Krickstein is the youngest men's player to make the quarterfinals of the U.S. Open (in 1983), as well as the youngest to win a Grand Prix tournament. He won three tournaments last year to vault from a No. 94 ranking to No. 12 and now is No. 7.

"I didn't play anywhere near that level when I was 17," Lendl said.

The nice American kid turned sneaky and finally found his ground strokes in the second set. With a mix of lobs, slices, drop shots and killer forehands, he broke Lendl in four straight points in the first game, finishing with a hard backhand winner, then held for a 2-0 lead.

The two held serve until the seventh game, when Krickstein broke again with a powerful cross-court forehand. He held serve at love for the set.

"He started hitting it a lot harder in the second set," Lendl said. "Then I made an error in strategy and tried to hit it harder with him, and I started missing. I had to correct it to win the match."

McEnroe said he would have to serve better against a swift new Lendl, who contends he is hitting the ball as well as he ever has. The two have met 21 times, with McEnroe holding a 12-9 edge. He has won four times on clay to two for Lendl, including Lendl's five-set victory in last year's French Open final.