WIMBLEDON, ENGLAND, JULY 5 -- Wimbledon, men's version, is a whodunit, a throat-tightening page turner played out among three champions in Ivan Lendl, Boris Becker and Stefan Edberg, and a mysterious stranger in Goran Ivanisevic.

The early days were suspenseless, the intermediate rounds impatient preludes, and finally the tournament begins in earnest with the semifinals Friday. Lendl meets Edberg, whose outward serenity hides a dangerous streak. The mercurochrome-stained defending champion Becker meets an unseeded revelation in Ivanisevic.

Edberg, the quiet 1988 champion, calls it "crunch time." Lendl, 30, seeking a title that long has eluded him, no longer can rely on his top seeding and role as favorite to get through. "Throw all the papers and forms out the window," he said.

The unknown factor is Ivanisevic, a boldly confident 18-year-old who has served nearly 20 aces a match to achieve his first semifinal. He is a lean 6 feet 4 with a slashing two-fisted backhand, and the first Yugoslavian man in the semifinals since Slobodan Zivojinovic in 1986. He has a precedent against Becker, upsetting him in the first round of the French Open in May with 19 aces, almost unfathomable on clay.

"Now it's going to be difficult," Ivanisevic said. "In semifinal everything is open, you know. You are going to have a lot of trouble, I think, against me. I am going to give my best match without pressure. He is the one defending the title, he is going to have pressure, not me. And maybe we see what's going to happen."

Last year Ivanisevic was a qualifier who made his way into the quarterfinals of the Australian Open. Now ranked No. 38 with an arrow pointing straight up, he has seared the service box here with 92 aces in five matches. That performance has made him a crowd favorite, along with his rapidly spoken, fractured English.

He has given up trying to explain the pronunciation of his name (Ee-vah-nee-seh-vich) and is unmoved by his newfound popularity. "Maybe they like, maybe they don't like, I don't care," he said.

Immaturity has been Ivanisevic's one hindrance and his Hungarian coach, Balazs Taroczy, is trying to cure him of taking mental strolls. He has an appealing, wide-eyed expressiveness on the court, which sometimes manifests itself into tantrums and digs at the grass with his racket.

"One point yes, one point no," he said. "When I am quiet, I can concentrate much more. When I am throwing the rackets and talking to the umpire, then I lose my concentration. But it is much better, I think; I am improving."

How 22-year-old Becker reacts to this reflection of his former self will say much about whether he is fit enough to win his fourth Wimbledon title. Becker's task is to convince Ivanisevic that an unseeded player does not belong here.

Of the 15 nonseeds in semifinals here since open tennis began in 1968, only two have made the final: Chris Lewis, who lost to John McEnroe in 1983, and Becker, then 17, who defeated Kevin Curren for his first title in 1985.

Becker's form has steadily improved throughout the tournament and he has become a different player since losing at the French and in straight sets to Lendl at Queen's Club. No. 2 Becker has dropped just two sets thus far, none since the third round, for the easiest passage of the four. He is a bedrock in Wimbledon semifinals, never failing in four previous appearances.

"I am in better shape," Becker said. "I've had a lot of sets on the grass and I've played strong opponents, and I think I'm better than I was {in Paris}. I think I'm better even than I was last year in this tournament. To get through I had to play really good tennis, and I did."

Lendl will confront a moment of truth against No. 3 Edberg, his first seeded opponent and one fully capable of ruining his hopes for a first title. Edberg is in his fourth straight Wimbledon semifinal, reaching the finals the last two years.

"I feel I'm playing well enough to beat him," Edberg said. "Now it starts to get really, really exciting. We will have to wait and see."

Lendl's play has not been quite as efficient as it was against Becker at Queen's Club and he has dropped sets in four of five matches. But this also is the first time he has come this far without struggling through at least one five-set match.

"You have to be in the semis if you want to win," Lendl said. "I think everybody has an equal chance now to win. I'm in the semis. I'm happy."