LONDON, JUNE 21 -- For 50 weeks, they prepare. For two weeks, they play. Today, the trucks brought in the last of the equipment, the wet grass courts were locked up and closed off to the players and the last bits of paint were applied around the grounds.

In 24 hours, the preparation will be over and the play will begin. Not at 2 p.m. precisely as tradition dictated for so many years, but at 12:30 p.m. At that hour, play on all 16 outside courts begins. Several years ago, the All England Club decided it needed extra time to complete play each day and, much to the horror of many, bowed to reality by starting before 2.

But on Centre Court and Court 1, that hour remains sacred, so it will be 90 minutes after matches such as Todd Witsken-Steven Shaw, Dianne Balestrat-Jenny Byrne and Peter Doohan-Alex Antonitsch have begun that Boris Becker will walk to Centre Court for the traditional opening match.

Becker, the two-time defending men's champion, is the top seed here and the favorite to begin Wimbledon's second century the same way he ended its first, by winning the men's singles title. He begins his defense with a match against Karel Novacek of Czechoslovakia. On clay, this would be a potentially dangerous match for Becker. Here, he should cruise.

Once, the first day was reserved strictly for the men. That, too, has changed, although only slightly. Sixteen women's matches will be played Monday, four involving seeds. The highest-seeded woman to play -- and the only one on a show court -- will be No. 7 Gabriela Sabatini. She opens against American Barbara Gerken on Court 1 right after Ivan Lendl, the No. 1 player in the world but the No. 2 seed here, plays his first match against qualifier Christian Saceanu.

All the traditions are in place: Becker playing Monday at 2 p.m.; women's champion Martina Navratilova playing her first match Tuesday at 2 against West German Claudia Porwick and, naturally, the rain.

Before today, when the sun popped in and out of clouds all day, it had rained in London every day in June. The papers are full of stories about the rainiest June in 25 years -- not to mention the tabloid stories about the personal lives of all the players.

Ah, welcome to Wimbledon.

There is an interesting twist this year: The women have no clear-cut favorite. The men do. This is a reversal from the recent past, when Navratilova and Chris Evert were the only women given a reasonable chance of winning.

Now, with Navratilova, who has won here seven times including five in a row, winless in 1987 and Evert a semifinal loser in her last three Grand Slams, they suddenly are vulnerable. But, unlike Steffi Graf in the French Open, no one is clearly poised to step into the breach.

Graf is the second seed and has a favorable draw. But she has not played a grass court tournament since playing here two years ago. Although she has not played poorly on grass -- reaching the round of 16 here in 1984 and 1985 -- she is not the confident player that she is on clay or a hard court.

Still, she has won 39 straight matches this year and, with Navratilova and Evert in the top half of the draw along with Helena Sukova, who beat them back to back to take the Eastbourne title Saturday, Graf has a chance to go far here. So do Hana Mandlikova and Pam Shriver. They are in the lower half of the draw with Graf and each must look at this as a golden chance to win this tournament.

Although much of the attention has focused on the teen-age whiz kids -- Graf and Sabatini -- Mandlikova and Shriver have moved into tennis middle age. Mandlikova is 25 and Shriver will be 25 on July 4, the day of the women's final. Mandlikova has won three of the four Grand Slams -- two Australians, one French and one U.S. Open. She reached the final here last year and, when her game is sharp, is as talented as anyone.

She is seeded to play Shriver in the quarterfinals. Shriver, who was stunned here in the first round last year by Betsy Nagelsen, is fit and ready but questioning herself at crucial moments just as she always has.

Saturday at Eastbourne she had Navratilova all but finished, leading her by 2-0 and 40-0 in the third set. Then she missed an easy backhand volley, went into a funk and, kicking and screaming, lost the match. "I just need a little bit of belief in myself," Shriver said. "I know I have the talent on grass . . . I'm not interested in getting to the quarters or semis at Wimbledon. I'm interested in winning."

She might never have a better chance than this year. "It would certainly be a great birthday present," Shriver said. "I just want to win one of these before I say so long."

Lendl feels about the same way about this tournament. He has won five majors -- three French and two U.S. Opens, but last year was his first Wimbledon final and Becker wiped him out in three sets.

On grass, Becker is certainly the favorite, especially with John McEnroe home resting a sore back. Becker's half of the draw has Mats Wilander, murder on clay but beatable on grass; the venerable James Scott Connors, who is playing well enough to make some noise; Tim Mayotte, the best U.S. hope on this surface, and Pat Cash, a legitimate dark horse who made the semifinals in 1984 and the quarterfinals last year.

If the seedings held, Becker would play improving American David Pate in the round of 16, Connors or Mayotte in the quarterfinals and Wilander or Cash or perhaps Yannick Noah (unlikely) in the semifinals. "I'm feeling very confident," Becker said, after coming from behind to beat Connors in the Queens Club final last Monday. "I think, certainly, I can win Wimbledon again, but I'll have to serve better there than I did here."

Lendl's half includes Stefan Edberg, who twice has won the Australian but never played well here, Miloslav Mecir, Andres Gomez, Henri Leconte and Kevin Curren.

But, as always, there will be upsets just as certainly as there will be rain and screaming tabloid headlines. The 50-week wait is ended. TODAY'S FEATURED MATCHES Centre Court

Boris Becker (1), West Germany, vs. Karel Novacek, Czechoslovakia; Pat Cash (11), Australia, vs. Marcel Freeman, Los Angeles; Mikael Pernfors, Sweden, vs. Robert Seguso, Sebring, Fla. Court 1

Christian Saceanu, Romania, vs. Ivan Lendl (2), Czechoslovakia; Gabriela Sabatini (7), Argentina, vs. Barbara Gerken, Calabassas, Calif.; Tim Mayotte (10), Bradenton, Fla., vs. Jean-Philippe Fleurian, France. Court 2

Stefan Eriksson, Sweden, vs. Stefan Edberg (4), Sweden; Stuart Bale, Britain, vs. Brad Gilbert (12), Piedmont, Calif.; Mats Wilander (3), Sweden, vs. Gary Muller, South Africa. Court 3

Andrei Olkhovski, Soviet Union, vs. Andrew Castle, Britain; Carling Bassett, Canada, vs. Sabrina Goles, Yugoslavia; Todd Nelson, San Diego, vs. Paul McNamee, Australia. Court 4

Todd Witsken, Carmel, Ind., vs. Stephen Shaw, Britain; Marie Christine Calleja, France, vs. Lori McNeil (11), Houston; Stephen Botfield, Britain, vs. Mel Purcell, Atlanta; Mike Bauer, Lafayette, Calif., vs. Emilio Sanchez (14), Spain. Court 5

Dianne Balestrat, Australia, vs. Jenny Byrne, Australia; Gary Donnelly, Scottsdale, Ariz., vs. Chris Bailey, Britain; Roland Stadler, Switzerland, vs. Richey Reneberg, Houston; Ken Flach, Sebring, Fla., vs. Roberto Saad, Argentina. Court 6

Guy Forget, France, vs. Thomas Muster, Austria; Paul Annacone, Knoxville, Tenn., vs. Milan Srejber, Czechoslovakia; Kathleen Horvath, Largo, Fla., vs. Csilla Cserepy, Switzerland; Mike Leach, Atlanta, vs. Jan Gunnarsson, Sweden. Court 7

Sylvia Hanika, West Germany, vs. Iowna Kuczynska, Poland; John Fitzgerald, Australia, vs. Jakob Hlasek, Switzerland; Juan Avendano, Spain, vs. Johan Kriek, Naples, Fla.; Bill Scanlon, Dallas, vs. Tony Mmoh, Nigeria. Court 8

Alex Antonitsch, Austria, vs. Peter Doohan, Australia; Terry Holladay, Del Mar, Calif., vs. Laura Garrone, Italy; Amos Mansdorf, Israel, vs. Nick Fulwood, Britain; Pavel Vojtisek, West Germany, vs. Martin Laurendeau, Canada. Court 13

Joakim Nystrom (13), Sweden, vs. Henrik Sundstrom, Sweden; Helen Kelesi, Canada, vs. Manuela Maleeva (8), Bulgaria; Sergio Casal, Spain, vs. David Pate (15), Las Vegas. Court 14

Slobodan Zivojinovich, Yugoslavia, vs. Marc Flur, Durham, N.C.; Peter Fleming, Glen Cove, N.Y., vs. Jeremy Bates, Britain; Catarina Lindqvist (12), Sweden, vs. Kathy Jordan, King of Prussia, Pa.