OCEANPORT, N.J., JULY 31 -- The 3-year-old championship is on the line Saturday at Monmouth Park -- and so is the judgment of trainer Jack Van Berg.

The $500,000 Haskell Invitational Handicap has attracted the three top horses of this age group for an eagerly awaited showdown (WJLA-TV-7, 4:30 p.m.). Alysheba won the Kentucky Derby and the Preakness. Bet Twice ran away with the Belmont Stakes by more than 14 lengths. Lost Code wasn't nominated for the Triple Crown series, but he has won seven races in a row.

This would have been a fascinating confrontation under any circumstances, but interest in the Haskell has been fueled for weeks by controversy over the drug Lasix. Alysheba was treated with the antibleeding medication when he beat Bet Twice, but couldn't use it for the Belmont. He qualified to use Lasix in the Haskell because of some loopholes in the New Jersey rules, infuriating the owner of Bet Twice, who threatened to skip the Haskell as a result.

But Van Berg abruptly put an end to the controversy this week when he announced that Alysheba would run without Lasix. He said he made the decision because Alysheba's next start will be in the $1 million Travers Stakes at Saratoga in New York, where Lasix is forbidden. "There would be no point in running on it here and then going to Saratoga and not being able to use it," Van Berg said.

In the Haskell, however, Alysheba has nothing to gain and everything to lose by forgoing Lasix. If Bet Twice beats him here, Van Berg will be widely second-guessed for giving up Alysheba's proven advantage over his rival.

Van Berg's decision hasn't wholly eliminated the impact of Lasix on this race. Lost Code, a bleeder, was transformed into a star by the medication. His career record without Lasix is one for nine; with Lasix he is seven for seven. Trainer Bill Donovan won't run his colt without it, so he won't be in the Travers.

The Haskell may well be the only meeting of these three colts, adding to its championship significance. For a day or two, this confrontation seemed threatened by a skin rash developed by Alysheba. Van Berg was upset by it, but yesterday he said, "I think we're in good shape. He had a little girth itch -- it probably had something to do with the heat -- but it's been treated. I don't like it, but I don't think it will hurt him."

With the principal rivals in good condition, and appearing to be evenly matched, the 1 1/8-mile Haskell may well be decided by pace and jockeys' tactics.

The two outsiders in the five-horse field, Clever Secret and Born to Shop, seemingly don't have a chance to win, but they could have a significant impact on the outcome. If either, or both, can challenge Lost Code for the early lead, they may soften him up for a late run by Alysheba or Bet Twice.

But if Lost Code and jockey Gene St. Leon can control the pace, as they have in most of their races, the colt will be hard to catch. And rival trainers know it.

"We're not going to let anybody steal this from us," Van Berg declared. But neither he nor his horse may be able to do anything about it.