Laz Barrera brought his colt Flying Nashua here from California, nursed him through a troublesome foot injury, put the finishing touches on his training and entered him in the Kentucky Derby. But this morning he was stunned to learn that he would not be allowed to run.

Churchill Downs limits the number of starters in the Derby field to 20, with preference going to the entrants with the highest career earnings. Until this morning, Flying Nashua had seemed to be safe, ranking 20th on the list of 22 horses pointing for the Derby.

He did, at least, until trainer Jose Martin, who already had entered his filly Wayward Lass in Friday's Kentucky Oaks, decided to put her name in the entry box for the Derby, too. Her presence bumped Flying Nashua into 21st place on the list and out of the race. Martin still may run Wayward Lass in the Oaks and scratch her from the Derby, but whatever he does, Barrera's horse is out.

Marin trains another Derby starter, Noble Nashua, whom Angel Cordero Jr. had been riding until he elected to take the mount on Flying Nashua, instead. Some cynics suspected a bit of vindictiveness in Martin's actions this morning, but the trainer said no.

"Genuine Risk started all of this," he said, refering to the filly who won last year's Derby. "Wayward Lass runs pretty good in the mud and Noble Nashua does not. She is in the race, and we'll take a look at the weather conditions."

Martin's decision left Barrera almost in a state of shock. "I think the rule (limiting the field to 20) is as bad as the people who put the filly in. How can you be knocked out of the Derby with a horse of this caliber? You get a horse with a real shot ready for the Triple Crown and you have to sit it out."

Two other colts were bumped out of the Derby by the 20-horse limit: Law Me, who finished second to Proud Appeal in the Blue Grass Stakes at Keeneland, and Mythical Ruler, who was three for three this year after a victory in the Stepping Stone Purse here. Mythical Ruler's trainer, Fred Wirth, and owner Al Risen Jr., who had long dreamed of having a starter in the Derby, were crushed, too.

Even with the field to 20 entrants, the Derby is going to resemble a cavalry charge, making post positions an important factor, and some of the principal contenders were big losers in the draw for posts this morning.

Bold Ego and Cure the Blues, two of the speedsters in the lineup, were assigned posts 15 and 16. From there, their jokeys will have to hustle them to get decent early position, although they would have liked their horses to relax in the early stages of the race. Tap Shoes, another well-regarded colt, will start from post position 19.The No. 20 post went to Wayward Lass, the last-minute entrant, which Las Barrera would doubtless consider to be poetic justice.