Chris Fallica reacts to Kentucky Derby favorite Omaha Beach being scratched from the race because of an entrapped epigiottis. (0:44)

LOUISVILLE, Ky. -- Omaha Beach, the favorite for Saturday's Kentucky Derby, has been scratched, his trainer Richard Mandella confirmed to Churchill Downs on Wednesday afternoon.

Mandella told reporters that Omaha Beach has an entrapped epiglottis. The epiglottis is a triangle-shaped piece of cartilage that is at the base of the airway above the soft palate. Because of its location, an entrapped epiglottis can cause difficulties breathing and would make it difficult to run a race without reversing the issue.

"After training this morning we noticed him cough a few times," Mandella said in a news release. "It caused us to scope him and we found an entrapped epiglottis. We can't fix it this week so we'll have to have a procedure done in a few days and probably be out of training for three weeks. We'll have to figure out a whole new game plan."

The trainer told The Associated Press that Omaha Beach will have surgery in Kentucky in the next few days and will be sidelined for two to three weeks. The ordeal will knock him off the Triple Crown trail.

"It's such a disappointment, but we'll fight again,'' Mandella told the AP. "We won't be out a long time.''

Jockey Mike Smith, who chose to ride Omaha Beach over Roadster in the Kentucky Derby, is now left without a mount. Trainer Bob Baffert told Sports Illustrated that he is sticking with jockey Florent Geroux for Roadster.

"I'm a little bummed out, but the horse is OK and we're going to be all right,'' Smith, who rode Baffert's Justify to victory last year en route to the Triple Crown, told the AP by phone. "The good news is it wasn't anything that is life-threatening.''

Smith has three mounts on Friday's card at Churchill Downs and five Saturday.

"I'll be rooting for Roadster's connections big-time,'' he said. "I'll be a glorified cheerleader.''

With Omaha Beach out of the running, Churchill Downs oddsmaker Mike Battaglia revised the morning line to make Game Winner the 9-2 favorite for the 1¼-mile race Saturday.

Improbable and Roadster were installed as the co-second choices at 5-1, giving five-time Derby-winning trainer Baffert the top three choices in the 20-horse field.

At the Westgate Las Vegas SuperBook, Game Winner was installed as the new favorite at 4-1, followed by Roadster at 9-2 and Improbable at 5-1. Maximum Security (6-1), Tacitus (8-1) and Code of Honor (10-1) round out the top six betting choices at Westgate.

Omaha Beach's scratch is one of the most surprising pre-Derby developments in the past decade. Morning line favorite I Want Revenge scratched on the day of the 2009 Kentucky Derby because of a hot spot on his ankle, leading to a wild race in which 50-1 long shot Mine That Bird won on a sloppy track.

Late scratches for high-profile horses don't happen often right before the Derby, but there have been a few instances in modern times. Favorite Eskendereya was pulled out of the Derby and retired from racing six days before the 2011 edition of the race due to a leg issue. Uncle Mo, the 2011 second betting choice on the morning line, was also a late scratch due to a persistent illness.

Omaha Beach galloped Wednesday morning without any problem. Mandella, who has not won the Derby with six previous starters, was quietly confident. Baffert, who is looking to tie trainer Ben Jones for most wins in Kentucky Derby history, even called Omaha Beach the "horse to beat."

Also-eligible Bodexpress will now be able to draw into the field and will start from post No. 20 unless another horse scratches prior to the deadline. All horses from post positions 13-20 will move over one spot toward the rail.

The Associated Press contributed to this report.