OCEANPORT, N.J. (AP) _ Alysheba, winner of the Kentucky Derby and Preakness, has developed a severe skin rash just days before his showdown with arch-rival Bet Twice in the $500,000 Haskell Invitational Handicap on Saturday.

Trainer Jack Van Berg says the rash, called girth disease, is a fungus that ''looks worse than it is. You wouldn't think anything of it if this was any other horse.''

Van Berg said Wednesday he has been otherwise pleased with the colt's workouts at Monmouth Park, where he has been training for his first race since his upset loss in the Belmont Stakes.

''I don't think the rash will hurt him, but then nobody really knows,'' he said. ''But I do know this: if he's not right, I won't run him.''

Van Berg said Alysheba's impressive workouts played a role in his decision to race Alysheba without the anti-bleeding medication lasix. The horse ran with the medication in his wins in the first two steps to the Triple Crown, but was prevented by New York State regulations from using it in the loss at Belmont.

The colt was bathed in medicated soap and zinc oxide on Wednesday to combat the rash. A final pre-race workout was scheduled for today.