Months ago, I did something no clear-eyed handicapper should ever do: I fell in love with a horse.

Before Rhoman Rule ever had won a stakes race, I wrote that he was my pick to win the Kentucky Derby. On the day that future-book wagering for the Derby opened in Las Vegas, I bet him with gusto at 30 to 1. Since that time, I have liked almost everything he has done in his races, and I have not wavered in my belief that Rhoman Rule will be draped with roses Saturday afternoon.

But he does not come into the 111th Derby looking like a mortal lock, as I had hoped he would, because three of his rivals ran so well in their final prep races. Even in my infatuated state, I recognize that Rhoman Rule faces tough challenges from Spend A Buck, Tank's Prospect and Chief's Crown, all of whom appear ready to run powerful races Saturday.

There is great depth of competition in this 13-horse Derby lineup, with only a couple of the entrants clearly out of their element. Even so, I think bettors can safely throw out Proud Truth, the probable second choice in the wagering, and Stephan's Odyssey. They aren't good enough. Throw out, too, all the horses who made their reputations in California -- Fast Account, Skywalker and Floating Reserve; they're a bunch of bums. Throw out Eternal Prince; he won't go 1 1/4 miles under pressure.

Spend A Buck will be applying that early pressure, and he, too, may weaken after a fast early pace. But Spend A Buck's last race, his 9 1/2-length victory in the Garden State Stakes, was so freakish that he may be capable of anything.

My speed figures say that if he duplicates that performance, he will win the Derby by seven lengths and threaten Secretariat's track record. I doubt that he can do it without getting an uncontested early lead as he did at Garden State, but Spend A Buck has so much ability that he has to be considered a powerful contender.

If there is a destructive speed duel in the Derby, Tank's Prospect is the stretch-runner most likely to benefit from it. Trainer Wayne Lukas' colt never had looked like a star until he scored a smashing 6 1/2-length victory in the Arkansas Derby. Lukas' horses frequently have been disappointments at Churchill Downs, but Tank's Prospect has been run so lightly this year that he may just be getting ready to deliver his peak performance.

But as hard as it is to evaluate Spend A Buck and Tank's Prospect, I think the most enigmatic horse in the Derby field is the heavy favorite, Chief's Crown. The colt has won all three of his races this year after earning the championship of his age group as a 2-year-old, so plenty of unsophisticated people think that his credentials are unassailable.

But Chief's Crown has found himself in can't-lose situations all year. If Rhoman Rule had had the same campaign, I believe he would have won those races much more impressively than the Chief and would himself be acclaimed as the star of the Kentucky Derby.

The two colts have had parallel campaigns this year: one seven-furlong tuneup and two 1 1/8-mile stakes. In fact, they started their activity on the same day, March 2 at Gulfstream Park. Rhoman Rule ran seven-eighths of a mile in 1:22, looking far more explosive than Chief's Crown did in running 1:22 2/5.

Each horse then fell into an easy spot, finding himself as the lone speed horse in a stake at Hialeah. Rhoman Rule led all the way to win the Everglades in 1:47 4/5. Chief's Crown led all the way to win the Flamingo in 1:48 2/5. Rhoman Rule was beginning to look like the superior horse until the colts' final prep races -- both of which may have been very deceptive.

Chief's Crown again found himself as the lone front-runner in a dismal four-horse field at Keeneland, and led all the way to win the Blue Grass Stakes by 5 1/2 lengths in a fast time. His performance was widely acclaimed, but I have no doubt that Rhoman Rule could have demolished the same group just as easily.

Rhoman Rule, however, had the misfortune of running his final prep on a wet track at Aqueduct, against a very tough field in the Wood Memorial Stakes. Ordinarily, I wouldn't be inclined to excuse his third-place finish because of the track condition. "He didn't like the track" is the oldest alibi in the book.

But months earlier, in Florida, when I mentioned to trainer Angel Penna Jr. that I had a big future-book investment in his colt, his response was: "Just hope it doesn't rain in Louisville." He said his horse was a miserable performer on an off track, and neutral observers have said the same thing, too.

Penna would have scratched him from the Wood if he hadn't needed the prep race so badly. Under the circumstances, Rhoman Rule ran quite creditably, accelerating well around the turn before fading in the final eighth of a mile.

The move he made in the Wood may be an omen of what will happen in the Derby. While Chief's Crown is an even-paced runner, Rhoman Rule has the capacity to deliver an explosive burst of speed -- the kind of burst on the turn that often wins the Kentucky Derby. They will finish this way: 1. Rhoman Rule. 2. Tank's Prospect. 3. Spend A Buck. 4. Chief's Crown.