WIMBLEDON : Wheaton Win a Pain to Agassi : Men’s singles: Fifth-seeded player injures his thigh early, blows lead after being within two games of winning match.

It was late on the Fourth of July, approaching the twilight’s last gleaming, when David Wheaton of the United States flagged down the last of Andre Agassi’s offerings.

Wheaton stepped perfectly into the backhand volley, right shoulder pointed toward his target area in the deep forehand corner of Agassi’s court, and flicked the ball beyond Agassi’s final lunge. The 13,000-plus in the stands at Wimbledon’s Centre Court Thursday were on their feet immediately, sensing the need to applaud both the moment and the long struggle that had preceded it.

The scoreboard read that Wheaton had won, 6-2, 0-6, 3-6, 7-6 (7-3), 6-2.

That meant that the unseeded Wheaton will play No. 2 Boris Becker of Germany in one of today’s men’s semifinals. No. 1 Stefan Edberg of Sweden will face No. 6 Michael Stich of Germany in the other.

Becker had outlasted Guy Forget of France, 6-7 (7-5), 7-6 (7-3), 6-2, 7-6 (9-7); Edberg had continued to coast along without the loss of a set, beating Thierry Champion of France, 6-3, 6-2, 7-5, and Stich had taken out French Open champion Jim Courier, 6-3, 7-6 (7-2), 6-2.

The scoreboard for Wheaton-Agassi fell well short of doing the match justice. The story line had plenty of twists and turns and some good old-fashioned praise for the Stars and Stripes. Francis Scott Key would have had a lump in his throat.

Wheaton, 22, is from America’s heartland, Lake Minnetonka, Minn. He has two brothers and a sister, and his mother and father, Bruce and Mary Jane Wheaton, say that they have raised their children to be “supportive of each other and responsible to God in our actions.” David Wheaton once came close to blows with Brad Gilbert in the midst of a tennis match. Wheaton was angry, according to his father, because Gilbert had said something to David’s brother, John, that David didn’t like.

Thursday, Courier described his friend Wheaton as “an all-American boy . . . wearing an American headband.” Wheaton’s headband is red, white and blue, and he started wearing it during the Gulf War.

“I got a lot of fan mail; people really seemed to like it a lot,” he said. “It wasn’t really anything, just symbolic that I’m an American. . . . Now I kind of like it and I think it looks good.”

Wheaton attended Stanford for one year, played No. 1 in singles and doubles for the Cardinal’s NCAA championship team in 1988, then turned pro--three years ago to the day.

The major subplot in Wheaton’s victory was Agassi’s injury. Agassi, seeded fifth, said he hurt his right thigh in the first game of the match. “I came down after a serve,” he said, “and I felt something tear.” He was treated by a trainer three times in the first nine games and said later that he was more concerned with the injury than with the set being played.

“It was about the third game when I almost quit,” Agassi said, “but I decided it would just be too tough a time for me to walk off the court. For all these people have given me here, my main concern at that point was just giving them a good match. It was asinine to think I could win.”

That having been decided in his mind, Agassi, who said later that even if he had won, he probably wouldn’t have been able to play in the semifinals, then went off and followed his loss in the first set with 6-0 and 6-3 thumpings of Wheaton in the next two. How could somebody in such pain play such wonderful tennis?

“I think the injury was kind of new to me in the first set,” he said, “and I wasn’t really concerned with my game at that stage. I was wondering if I could continue. Then, once I made up my mind to fight through it, I think just the emotion of knowing that the balls have to stay within two or three rallies and David maybe getting a little apprehensive here or there made a big difference.”

Wheaton, who said he suffered a hyper-extended Achilles’ tendon, was more than a little apprehensive. He was basically all but finished, especially when Agassi took it to 2-4 and 0-40 on Wheaton’s serve in the fourth set.

“You could pretty much write it off at that point,” Wheaton said.

But the one person who apparently didn’t was Wheaton, who tossed five consecutive big serves at Agassi at that point, went on to eventually hit a few more big serves in a fourth-set tiebreaker, then ran through his stunned opponent in the fifth set.

“What made me feel the best about this match,” Wheaton said, “was figuring a way out of this, thinking through an almost hopeless situation--he was serving for the match--and somehow, I don’t really know how, figuring out a way to win.”

Although Agassi had a highly successful Wimbledon by most standards and has made friends of the British, he might still wonder how he figured out a way to lose this one. That thought could last well into dawn’s early light.

* END OF THE ROAD Fifteen-year-old Jennifer Capriati is eliminated in the semifinals by Gabriela Sabatini, 6-4, 6-4. C4