WIMBLEDON, ENGLAND, JUNE 30 -- There was a pervasive edginess at Wimbledon today, brought on by three more bomb scares and blustery wind that had a dangerous equalizing effect. Stefan Edberg and Michael Chang both had to recover from deficits over five tense sets before making the round of 16; Ivan Lendl left his third-round match uneasily incomplete.

Nobody was immune from the harassing 35-mph gusts at the All England Club, and only the telltale differences between seasoned champions and ambitious journeymen separated Edberg and Chang from their opponents. Third-seeded Edberg, the 1988 titlist, had his patience tried to the limit before he defeated Amos Mansdorf, 6-4, 5-7, 3-6, 6-2, 9-7, securing the match with two scorching winners after he was unable to gain a break point in the last set until the 15th game.

"I had to give everything I had," Edberg said. "It was very tough conditions, very tough to play, very gusty."

Chang, the 1989 French Open champion seeded No. 13, made one of his vintage recoveries from a two-set deficit to wear down Mark Kratzmann, 3-6, 4-6, 6-4, 6-2, 6-2. Chang's career record in five-set matches is 6-1, and with the victory he arranged a fourth-round meeting with Edberg, a rematch of last year's Paris final.

"I never like being down two sets, I don't think anybody does," Chang said. ". . . But you never know what will happen without giving yourself a fair chance to play the whole match until the last point is over."

While three suspicious packages were investigated by bomb crews and found to be harmless, the wind played all kinds of havoc, curling shots in and out, leaving them deep or short capriciously. Even the simple toss from ballboy to player turned into an adventure.

Top-seeded Lendl could not assert a lead over 125th-ranked Bryan Shelton, a former Georgia Tech all-American, winning a first-set tiebreaker but losing the second, 7-6 (7-2), 6-7 (4-7). The match was called under twilight and advancing clouds, and Lendl must mull the score and Shelton's last near-ace throughout the traditional idle Wimbledon Sunday, the match not to be resumed until Monday.

Martina Navratilova was taken aback when 21-year-old qualifier Karin Kschwendt broke her normally impregnable serve to open the match. But Navratilova is the No. 2 seed, and while Kschwendt is the best player to hail from Luxembourg, the difference quickly showed as Navratilova went on to a careful, 6-1, 6-1 victory.

"It wasn't easy, even if the score was," Navratilova said. "It was wicked out there."

While Lendl was struggling with Shelton on Court 1, the most serious of the trio of bomb alarms was occurring. Security forces cleared Centre Court and adjacent buildings at 7:35 p.m. when an unattended briefcase was spotted in the stadium. Three outer courts were cleared Thursday when a camera case was left on a boulevard. Unattended bags have been deemed cause for concern since a bomb exploded at a Tory club in London on Monday, injuring four.

A doubles match between Ken Flach-Robert Seguso and Patrick McEnroe-Jim Grabb was suspended and the lingering spectators were cleared. The scare lasted roughly 30 minutes. A bomb squad ascertained the briefcase was harmless.

Despite the miserable conditions, only one seeded player was upset. No. 9 Jim Courier had not dropped a set in two rounds, but he was eliminated by veteran Mark Woodforde, 7-5, 5-7, 7-5, 6-4.

Edberg never suspected he had such a threatening opponent in Mansdorf, whom he had beaten easily in three previous meetings. But today No. 34 Mansdorf had new resolve, while Edberg clearly was bothered by the uneven conditions, and it is impossible to express just how close their encounter was.

"He hit two better shots than myself," Mansdorf said. "That was it."

Edberg has been noticeably off his form, shaken by last month's first-round loss at the French Open. To pull through in such a difficult match may have been exactly what he needed to recover his confidence. Mansdorf was sullenly uncooperative, answering Edberg's big serves and silky volleys with his own massive deliveries, while the wind kicked up and stiffened the stadium flags. Edberg's disgust was evident as he fidgeted, repeatedly changed rackets and gestured to the sky through four sets.

The fifth set was a stalemate that included eight games won at love. Mansdorf five times held with shutout games, the last coming for a 7-6 lead. At that juncture he had lost just three points on his serve in the set. But by then it was a matter of nerve, and Edberg, winner of four Grand Slam titles, showed more of it.

"The top guy is going to play better on the big points," Mansdorf said. "That's the thing. And deep inside you know it, in the back of your mind. That's the difference, the slight mental difference. You know he's not going to give you the match."

Edberg held with an ace to even it at 7, then got the opening for which he was so carefully biding his time, unreeling the crucial winners. He gained 30-30 on Mansdorf's serve with a cracked backhand return winner down the line, screaming as it landed for a winner. That seemed to lend him confidence as he forced deuce twice, then landed two big strokes -- a forehand cross for his only break point of the set and a low drilled forehand that Mansdorf slapped into the net tape.

Edberg never gave Mansdorf a window to come back, holding serve with what was his third love game of the set. He delivered two service winners to end it after 3 hours 3 minutes.

"I think a match like this is probably going to do me a lot of good," Edberg said. "It's good to get one of these matches out of the way where you really have to fight. He really only gave me one chance, and I was lucky to take it."

Although Chang had a greater deficit, his match with Kratzmann lacked high drama, maybe because the Californian has been in this situation so many times and managed to dig himself out. Nor was his trouble with Kratzmann, ranked No. 55, entirely unexpected. The Australian the larger, more effective grass-court game, and defeated Chang, a counterpuncher, in two tiebreaker sets last week in a tuneup event.

Chang's matches rarely are easy ones simply because of his baselining style, and he is making a painstaking recovery from a fractured hip. So when he trailed by two sets to none, there was a ripple of alarm. But Kratzmann lacks stamina, while Chang has a habit of rising to big events: He has made at least the round of 16 in his last four Grand Slam tournaments, and never collapses.

"Whenever there is the slightest chance you have to take it, you just can't give up," Chang said. "I've had so many times when I've been down two sets and I kind of work myself back, play it point by point. I try to get that third set, and if I win the fourth set it's a whole new ballgame, and the fifth set is up for grabs. Then it's really a matter of just giving it all you've got in the last set."

That's exactly what happened. The turning point came when Kratzmann could not hold a 30-0 lead as he served at 4-5 in the third set. Chang unleashed two lunging winners that swung the momentum of the match, a scathing forehand return down the line for set point and another huge forehand cross to take it.

Chang's strokes by then were grooved, while Kratzmann began dumping easy volleys into the net. The fourth set was even through 2-2, when Chang broke to begin a four-game streak. Kratzmann was in the fifth set for only three games. Chang broke to go up by 3-1 as Kratzmann double-faulted and knocked an off-balance overhead into the net for 15-40. Chang then seized the game with a looping forehand winner off his ear.

Chang's impending meeting with Edberg naturally summoned all sorts of memories of last year's French Open final, when then-unseeded Chang defeated the third-seeded Swede over five sets. This will be their first encounter since Paris, and although Eberg is the favorite on the slick grass, observers have learned never to make predictions about Chang.

"I never count myself out," he said.