American Paul Chamberlin set back the Wimbledon preparations of comeback-minded Pat Cash, upsetting the 1987 champion, 6-4, 1-6, 6-1, on the opening day of the $450,000 Stella Artois Grass Court Championships in London.

"I've got a couple of weeks before Wimbledon starts to iron out a couple things and hopefully I will be playing well by then," Cash said after his fifth double fault ended the 1-hour 56-minute match on the Queen's Club center court.

Chamberlin, a Wimbledon quarterfinalist last year and ranked No. 71, was happy with the victory: "He is a tough player on grass and I know he is not quite up to his normal par, but for me to beat him is a major accomplishment in my career."

Chamberlin will next meet reigning Wimbledon champion Boris Becker.

Becker, who won his third Wimbledon crown last year, received a first-round bye as did the other top seeds in the 56-player field. Top-seeded Ivan Lendl and former Wimbledon champions Stefan Edberg and John McEnroe also got byes.

After rupturing his right Achilles' tendon last April, Cash sat out until returning to singles play in March. After three consecutive first-round losses, Cash put together consecutive runner-up and winning efforts in Seoul and Hong Kong to boost his world ranking from 626 to 142. . . .

Tim Mayotte said he will return to Washington next month to defend the Sovran Bank Classic title he won last year at FitzGerald Tennis Center. He will join top 20 players Andre Agassi, Brad Gilbert, Aaron Krickstein and Michael Chang in the 56-player field for the July 16-22 tournament.