Wimbledon, the world's most prestigious tennis event, begins its annual two-week run on Monday. In recent memory, picking the favorite was easy. Take John McEnroe and Martina Navratilova against the field, give odds of about 8 to 5. Not this year.

Although McEnroe and Navratilova will remain atop the oddsmakers' boards in London, neither is as feared as before on these fast grass courts.

McEnroe's confidence may be questionable after losses to Ivan Lendl at the Tournament of Champions and in the World Cup at Du sseldorf. In addition, he has a chronic problem with his left thigh, which he keeps bandaged. Still, he won this title in 1981, 1983 and 1984.

Lendl just lost the French Open final to Mats Wilander, on clay, but his confidence on grass is better than two years ago. Lendl is not a serve-and-volley player, though, so he will be vulnerable to a host of American college players who thrive on fast courts.

While McEnroe and Lendl both are 26, Jimmy Connors, a two-time Wimbledon winner, is 32 and, admittedly, has lost half a step. He very well may be the crowd's favorite this year. Following his loss to Lendl at the French Open and a subsequent first-round defeat by Mike De Palmer at a grass court event, Connors will have to establish some dominancy in the early rounds to bring himself to peak form.

Wilander could win it all. At 20, he already has two Australian Opens to his credit, so he knows grass courts. His second French Open victory two weeks ago gives him momentum, but the English hardly know him. He can walk the grounds of the All England club and few heads would turn. This lack of attention benefits his unassuming, laconic personality.

Several other players have excellent chances to do well, but are long shots to win.

Tim Mayotte loves grass courts and, as a winner of the Players' International this spring, this 1983 Wimbledon semifinalist should be tough. Wilander's Swedish compatriots Stefan Edberg, Anders Jarryd and Joakim Nystrom could make the semifinals. Johan Kriek could be a factor, as could Pat Cash, a young, athletic player who lost in the semifinals of the 1984 U.S. Open to Lendl.

Aaron Krickstein, the 18-year-old with a lethal forehand, is a question mark. He feels more confident on clay and probably will try to win from the base line. Brad Gilbert, Paul Annacone and Scott Davis are other talented young Americans who could score upsets.

The women's draw continues to improve in depth and quality each year, yet Navratilova and Chris Evert Lloyd dominate. They are the only two women entered who ever have won the Wimbledon singles, and between them they have done it eight times. They should once again meet in the finals.

The only five legitimate threats to jointly first-seeded Navratilova and Evert are Hana Mandlikova, Pam Shriver, Claudia Kohde-Kilsch, Kathy Jordan and Helena Sukova. Mandlikova has the talent to win and is perhaps the most graceful player on the planet but she suffers lapses in concentration frequent enough to cause occasional bad losses.

Shriver is formidable but prone to injury. She certainly is overdue to win her first Grand Slam singles title. This may be the one. Six feet tall, she can be dominant at the net.

Kohde-Kilsch also is tall, aggressive, and has a more than adequate serve. Jordan is, like Mandlikova, a superb athlete but possesses the weirdest strokes of all the top women. Her heavily underspun backhand makes her approach shot deadly but it lacks power.

Sukova, whose mother was a 1962 Wimbledon finalist, is improving quickly and is a potential semifinalist.

This Wimbledon may go down as a turning point for players with two-handed backhands. Manuela Maleeva and Kathy Rinaldi use that style, popularized by Evert, but otherwise it is losing favor among the best young players.

From the crop of relative newcomers, teen-agers Boris Becker of West Germany in the men's draw and Gabriela Sabatini of Argentina both play one-handed backhands. It may be that the world's leading teaching professionals are changing their approach to this shot. Becker is being hailed as Europe's next wunderkind and Sabatini, only 15, reached the French semifinals.

The All England club, a holdout against the trend, still has unequal prize money for men and women. But, under a formula worked out between the Wimbledon committee and the Women's Tennis Association, women's purses will not drop below a stated percentage of men's purses. At the U.S. Open, all prizes for men and women are the same.

When the Wimbledon checks are handed out, I expect to see Navratilova and McEnroe receive the big ones.