NEW YORK, SEPT. 11 -- All four of them have been in Grand Slam semifinals before. All four of them have won a Grand Slam tournament. Two of them have won the U.S. Open. But only one of the four men who will play in Saturday's U.S. Open semifinals is the overwhelming favorite to win a third straight Open title on Sunday.

That man is Ivan Lendl. He will play Jimmy Connors in the second semifinal after Swedes Stefan Edberg and Mats Wilander open the program at 10 a.m.

Lendl has won the last two championships here and has been in five straight finals. He has a 19-match winning streak here, dropping two sets during that time, none of them this year. On Wednesday, he destroyed John McEnroe with a display of power tennis not often seen, especially against a player of McEnroe's caliber.

"He's playing excellent tennis, as well as I've seen him play here," McEnroe said of Lendl after the 6-3, 6-3, 6-4 rout.

"I'm feeling very good right now, very confident," Lendl said. "But I know that each match gets tougher in a tournament like this."

Maybe, maybe not. Connors' presence in the semifinals at age 35 is a tribute to his endurance and tenacity. His record in this tournament is remarkable -- five titles, seven finals, 12 semifinals. But he has not beaten Lendl in their last 13 meetings, and in the best-of-five format, especially with Connors' sore right foot, a Connors victory would rank as a near-miracle.

"Five doctors have looked at it and haven't been able to figure out what's wrong," Connors said of his foot problem. "All I know is that it hurts."

Connors has not won since he beat Lendl in a final in Tokyo in 1984. But his intensity has not declined in proportion to his skills, perhaps because he's kept his expectations in perspective.

"It's no secret," Connors said. "Anything I do now is extra."

Connors practiced this morning and said his foot felt better. But he knows that beating Lendl, even with 20,000 people behind him, will be difficult. "I've had a really good year and I'm playing very good tennis," he said. "He's obviously very tough to beat. I've just got to go out and play the best I've played in a long time."

Even that might not be enough, given the roll Lendl is on. Since he defeated McEnroe in the final here in 1985, he has felt as if this is his tournament. He lives 45 minutes from here in Greenwich, Conn., and he has learned to shut out all the distractions: airplanes, food smells wafting into the stadium, crowds that almost inevitably pull for his opponent. Lendl just plays great tennis and goes home to play golf, read baseball box scores and watch Canada Cup hockey on television.

He has developed his own entourage, much like that other Czech expatriate, Martina Navratilova. Everywhere he goes he is trailed by his longtime girlfriend, 19-year-old Samantha Frankel; two agents; his coach, Tony Roche, and an Australian radio reporter. In short, Lendl is very comfortable here.

The Swedes are exactly the opposite. Before today's doubles final, they had never won a title here. This was Bjorn Borg's albatross; he lost four finals here. Wilander and Edberg each are in their second semifinal. Neither has reached the final here or at Wimbledon, their Grand Slam success coming elsewhere: Wilander has won two French Opens and two Australian Opens; Edberg the last two Australians.

"Maybe this will be the year," said Edberg, whose serve-and-volley style should favor him against Wilander. "I think if I play my best, I can beat anyone."

But for Connors, even his best may not be enough. He will have to return superbly and hope Lendl makes some mistakes to have any chance. Wilander will have to serve as well as he did in beating Miloslav Mecir in the quarterfinals if he is to upset Edberg. In all likelihood though, the final will be No. 1 against No. 2: Lendl vs. Edberg.

And the winner? Three guesses, and the first two don't count.

U.S. Open Notes: David Wheaton, the 17-year-old junior who took Ivan Lendl to three sets in the Sovran Bank/D.C. National Tennis Classic in Washington in July, advanced to the final of the junior boys singles here with a 6-4, 7-6 (7-3) victory over David DiLucia.

Wheaton, seeded sixth in the boys division, will face the Soviet Union's unseeded Andrey Cherkasov, a 6-4, 6-3 upset winner over top-seeded Jason Stoltenberg of Australia, in the final.

Wheaton, who is from Excelsior, Minn., was a wild-card entry in the Washington tournament. Here, he has won five straight matches without dropping a set, including a 6-0, 6-3 win over third seed Diego Nargiso . . .

Saturday's schedule for the men's singles semifinals and the women's final will be Mats Wilander-Stefan Edberg at 10 a.m., followed by Jimmy Connors-Ivan Lendl. The women's final will follow. The early start may be because of the threat of inclement weather in the New York area and because the Mets are engaged in a critical three-game series against the St. Louis Cardinals across the street.