WIMBLEDON, ENGLAND, JULY 1 -- While aging Ivan Lendl and Martina Navratilova argue the semantics of obsession, Steffi Graf looks wan and Boris Becker is tired and ill-tempered. Rival generations with separate wants and pressures are on collision courses as the second week of Wimbledon begins.

After the traditional idle Sunday, the tournament resumes with the round of 16 and the promise that this curiously symmetrical foursome will draw ever closer. Lendl, 31, and Navratilova, 33, are Czechoslovak expatriots with dwindling seasons before them, and seek Wimbledon titles that would put them in historical perspective. Becker, 22, and Graf, 21, West German childhood friends, already are discovering the exhausting price of defending their championships.

The first part of the fortnight was taken up with bomb scares, the upset of John McEnroe and retirement of Hana Mandlikova from singles play, and bored philosophical debates on everything from how loudly a player should be permitted to grunt to the broken arm of Prince Charles.

Navratilova and Lendl deny they are "obsessed" with Wimbledon, Lendl preferring "passion," Navratilova thumbing through the dictionary for terms such as "rational reverence." Becker cited fatigue, Graf endured ugly tabloid stories about her family and a nagging sinus problem, flying home overnight for treatment.

"It hasn't been very easy and it's not going to get easier," Becker said, and he spoke for all of them.

Now they encounter mounting pressures and opponents who might threaten them. Navratilova meets her first seeded opponent in No. 14 Judith Wiesner. Lendl will resume a so-far difficult third-round match with Bryan Shelton. They split two tiebreakers -- Lendl taking the first, 7-2, and Shelton the second, 7-4 -- before darkness halted play on Saturday. Shelton, 24, is a former all-American from Georgia Tech who has progressed from No. 455 in the world to No. 125 in two years.

He was not intimidated against the top seed, capturing the second set with a near ace, much like he did in seizing the first set from Jimmy Connors in last year's U.S. Open before falling in four.

Becker will meet 1987 Wimbledon champion Pat Cash. Graf faces a long-awaited first match with Jennifer Capriati and a frightening reflection of herself a few years ago, before she was burdened with the top ranking.

Graf normally might be expected to overcome 12th-seeded Capriati easily, the teenager cheerfully struggling somewhat with inexperience in her Wimbledon debut. But Graf's physical and emotional conditions have become sizable question marks. She maintains she is unaffected by the controversy surrounding her and the rise of the new teenagers, and whether she can reassert her dominance is one of the more compelling issues of the tournament.

"I think I'm still the same," Graf said. "It doesn't depend if I win here or not, it's not going to make a big difference. There's not going to be a big change about it. I mean, it's for myself. I want to try and win it, definitely, but it is not for other reasons. It's just because it's Wimbledon and I want to try and get it."

Beyond Capriati, Graf could face the spectre of Monica Seles, 16, the third seed who has beaten her twice consecutively, including the French Open final. That is if Seles, playing in only her second Wimbledon, can move through a difficult draw that could pit her against No. 5 Zina Garrison in the quarterfinals.

Ironically, Graf mused this week that she may not play much beyond 25, citing increased pressures and the fact that she started so young. She was 15 when she burst onto the scene by making the Wimbledon round of 16 in 1984. She now meets the youngest player ever to win a match here, and a zealous opponent.

"I can't wait," Capriati said. "I've always wanted to play her."

It should be an entertaining collision between the present and the future and their belting ground strokes. Even Navratilova expressed interest in seeing it. "That's about as special as you can get," she said.

Navratilova faces Wiesner, but her real opponent is the toll a two-week event can take on a 33-year-old body and mind. Her drive for a coveted, record-breaking ninth title should otherwise be untroubled until the final. She is playing considerably better than last year, when she was nearly beaten in the third round by a qualifier. But there are unforeseen hazards strewn all over the courts in the second week of any Grand Slam event, much less the worn grass of Wimbledon.

"No matter how well you prepare, things can still go against you," she said. "Whether it's a little bit of fuzz falling down and fogging up your glasses, or the sun is really low and the shadows come across the court, or you have a little ankle sprain and you can't move quite as well, or the knee starts acting up. You can't guard against it."

Lendl ran into one of those situations when darkness set in Saturday. He should not have undue trouble with Shelton once they resume Monday. Shelton caught Connors off guard in the second round of last year's Open with his big serve. He won a first-set tiebreaker, but ultimately was routed, 6-7, 6-2, 6-2, 6-2, on Center Court.

Lendl also must mull an increasingly difficult draw, while Becker's way was largely cleared by the first-round upset of No. 4 McEnroe and five other seeds. Becker could use some easy matches: He's looking drawn and is complaining of a difficult schedule since he claimed both the Wimbledon and U.S. Open titles last year. One remaining threat is No. 7 Brad Gilbert, who has beaten him four times and thus would be a dangerous quarterfinal opponent.

"It's a problem for me to play 11 and a half months of tennis," Becker said. "I've never had a problem psyching myself up for the Grand Slam tournaments, but the other ones I don't like to play so much. I like to do other things, just not spend so much time on the tennis court. I don't think anybody likes to work for a whole year. Same thing with me."

Lendl faces a potential semifinal meeting with No. 3 Stefan Edberg or No. 13 Michael Chang, who stunned both Lendl and Edberg in winning the 1989 French Open. Chang and Edberg's round-of-16 match will be their first since their five-set Paris final. Edberg is favored, more at home on his beloved grass courts.

The Swede has been somewhat forgotten in all of the discussion over whether Lendl can claim his first Wimbledon after so many frustrating years, or if the weary Becker can raise his game enough for a fourth title. It was under similar circumstances that Edberg intruded and won here in 1988. He doesn't mind the indirect slight, quietly commuting everyday from his home in Kensington and enjoying the lack of pressure.

"I guess that's the way I like it," he said. "I just take it as it is. Lendl is playing well on the grass and a lot of people are talking about him because he put in the big effort to win this one. And Becker, of course there is always a lot of talk about him when Wimbledon comes up. I am somewhere behind there. It is sort of a good position to be in. Now I'm in the second week and I know if I play well I can go all the way."