The U.S. Open did its Wimbledon act today. Not with grass or strawberries and cream. With rain. Lots of rain. And hail, thunder and lightning. There were reports that several small tornadoes touched down in the area of the National Tennis Center.

All day, the weather threatened. The morning was hazy and humid and the sky grew darker and darker. Finally, shortly after 4 p.m., the storm struck.

Within 30 minutes, parts of the Stadium Court were under several inches of water. Trees were down all over the grounds -- two split in half by lightning. several corporate hospitality tents had collapsed and the press box literally was rocked by the force of the storm. Day 4 of the tournament had come to a halt.

There were two mild upsets before the downpour. Scott Davis, the No. 15 seed in the men's draw, lost to Brian Teacher, 6-3, 7-6 (7-4), 6-3. Davis is a rising star but occasionally plays flat tennis, and that was the case today. Teacher, at 30, is going the other way. Once ranked 12th in the world, he is 89th now but is still a decent player on a fast surface. He quickly took advantage of Davis' mistakes in earning a convincing victory.

The other seeded player to lose was Andrea Temesvari, No. 16 among the women. Her second-round loss was a mild upset, partly because she had been playing much better recently after a horrid spring and partly because her winning opponent was qualifier Caroline Kuhlman, a 19-year-old from Lakeside Park, Ky., who is ranked No. 172 on the women's computer.

Kuhlman, a member of the Junior Federation Cup team, looked like an easy mark for Temesvari when she dropped the first quickly. But she then turned the match around, going on to a 2-6, 6-2, 6-2 victory.

The big names continued to advance with little difficulty. Jimmy Connors moved to within one victory of Vic Seixas' all-time tournament record of 75 singles victories with a 6-3, 6-4, 6-2 win over Hank Pfister. Henri Leconte, the quick Frenchmen with all the shots, defeated countryman Guy Forget, 6-4, 6-4, 6-4.

Forget, who upset Wimbledon finalist Kevin Curren in the first round, simply didn't have enough shots to beat the often-spectacular Leconte, who may be Connors' biggest obstacle en route to the semifinals.

The only other seeded man to complete his match was No. 11 Stefan Edberg, an easy 7-5, 6-3, 6-4 winner over Ken Flach. Five women's seeds advanced, led by No. 4 Pam Shriver, who struggled a little before beating Chinese defector Hu Na, 6-2, 7-6 (7-5). No. 6 Zina Garrison, No. 8 Manuela Maleeva, No. 11 Steffi Graf and No. 13 Catarinia Lindqvist all won in straight sets.

The most disappointed loser of the day may have been Regina Marsikova of Czechoslovakia. Marsikova, coming back after almost four years away from the tour because she was found culpable in a fatal automobile accident in Prague, lost her first set today to Leigh Ann Thompson, 6-4. But she was leading, 5-2, in the second set when she fell and sprained her left ankle. She was forced to retire.

Several players' matches were stopped by the storm, including one involving Ivan Lendl, who was leading Bill Scanlon, 6-2, 2-0. Martina Navratilova and Yannick Noah had been scheduled to play tonight.

The most impressive winner today may have been Connors. Three days short of his 33rd birthday, Connors still can make a serve-and-volley player such as Pfister look almost helpless. Service returns still whistle off his small racket and his intensity still is evident.

"I still enjoy the tennis," Connors said, repeating what has become his standard victory speech. "I still love to grind it out with the younger players out there (Pfister is 30) and feel like I can compete."

Connors can still compete but there is some question whether he still can win. He has not won a tournament since October. His next opponent is another rising Frenchmen, Thierry Tulasne, and, if he wins, would likely face Edberg after that. With Curren gone, Connors stands a decent chance of reaching the semifinals here for the 12th straight year.

"If people want to bury me, then make me a tombstone," he said. "But don't put it on top of me yet. I'm out there trying to prove that I can still play the game and win tournaments, including this one.

"Never fear, though, I may be around when it counts in this thing."

He may well be. So may Leconte, who reached the quarterfinals in the French Open -- beating Noah -- and Wimbledon -- beating Lendl. Today, playing on the noisiest court at the National Tennis Center -- No. 3 -- Leconte and Forget displayed what has become the French style.

Leconte would smack a winner, Forget would smack one. Then each would make an error going for a winner. There was an added twist: if one player felt the other had been treated unfairly by a line call, the other one overruled the call. That is the way the French play.

It is not the way Lendl and Scanlon play. Their first set, one-sided as it was, took a long time because each man kept stopping to dispute calls. There was even a brief argument over whether to stop play because of the storm.

In another suspended match, ninth-seeded Miloslav Mecir was trailing David Pate, 6-4, 6-0, 0-1.

The storm left the grounds a shambles. Players were asked to leave the locker room and lounge areas as quickly as possible because several wires were down just outside the building and because of flooding in the rooms. Four spectators were treated for injuries, the most serious being a possible broken arm.

The postponed matches will be made up Saturday if all the courts can be cleaned up in time for play to begin as scheduled (television coverage is scheduled to begin at 12:30 p.m. on WDVM-TV-9). Only about 20 matches were lost because of the rain. Of more concern to USTA officials is the damage to the facilities.