"I'm sick and tired of talking about Lasix," Jack Van Berg said yesterday at Monmouth Park, where everybody has been talking for weeks about Lasix and its probable effect on the rematch of Alysheba and Bet Twice.

Most of the world believes that Alysheba lost the Belmont Stakes because he couldn't use the anti-bleeding medication in New York, but that Lasix would give him the edge over Bet Twice in the $500,000 Haskell Invitational. Bet Twice's owner and trainer expressed their outrage that New Jersey's rules would permit Alysheba to use Lasix.

Van Berg consistently has disputed the notion that Alysheba needs the drug, and on Saturday he will try to prove it in a bold way. "I'm going to tell you flat out," he said yesterday. "I'm not going to use Lasix."

The announcement epitomized the reasons Van Berg is one of the most respected men in his profession. Not only has he won more races than any trainer in history, but he is unswervingly honest and forthright. The vast majority of trainers would swear on their mother's grave that there is nothing wrong with the horse, that he doesn't need any medication -- and then use it, anyway. Van Berg has the courage of his convictions. He said he is more concerned about a skin rash that has been bothering Alysheba this week than any respiratory problems.

There's just one trouble with his position. His convictions in this case probably are dead wrong.

Van Berg and various experts could contend before the Belmont that Alysheba didn't really need Lasix, which he had received only as a "precaution" after he underwent an operation for an entrapped epiglottis. That argument seemed reasonable until June 6.

But if Alysheba doesn't need Lasix, then why did he beat Bet Twice when he received the medication before the Kentucky Derby and the Preakness, and then lose to him by 14 lengths in the Belmont Stakes?

"I don't know how you can say Lasix had anything to do with it," Van Berg insisted yesterday. "In the Belmont, the horse got turned sideways entering the stretch and still got beat for second by only a nose and a neck."

To say the least, this is a charitable interpretation of Alysheba's performance. Yes, Alysheba did get bumped entering the stretch, and the incident did cost him second place. But that doesn't mean that the significance of the whole race can be dismissed.

Alysheba was hopelessly out of contention when he reached the final turn of the Belmont. He got into trouble because he was not quick or sharp enough to zip past the horses who wound up getting in his way. If he had not had a straw in his path, he probably would have lost by 10 lengths instead of 14. What would Van Berg have said then?

Understanding the outcome of a race is a tricky business because so many dozens of crucial factors are involved. After a race, different people will say that the key was pace, weight, track bias, etc. But in the Belmont, it was hard to find any other reasonable explanation for Alysheba's showing except the absence of Lasix. He had trained well; he figured to be suited by the distance, and high-class horses rarely have random "off days."

Racing fans may want to root for Van Berg in the Haskell, because his decision to forgo Lasix was a gutty and honorable one, but it wouldn't be advisable to bet on him under these conditions. In fact, Van Berg might have conceded the advantage to the third contender in the Haskell field, the confirmed bleeder Lost Code, who has won seven straight races with the aid of Lasix.

Trainer Bill Donovan has said he never will run his colt in New York or any place where he can't use Lasix. In New Jersey, he said, "I will use anything they let me use."

After Saturday, Van Berg might be adopting the same position for Alysheba.