With a crowd gathered at the Churchill Downs rail Thursday morning, exercise rider James "Bobo" Brigmon takes Kentucky Derby entrant Done Talking for a jog. The 138th running of the Derb is Saturday.

Exercise rider Carlos Rosas takes Kentucky Derby entrant Sabercat for a morning gallop Thursday.

Exercise rider Hector Ramos takes Gemologist for a spin around the Churchill Downs track. Gemologist enters the Kentucky Derby 5 for 5 lifetime and is 6-1 on the morning line.

Two prime Kentucky Derby contenders meet as Hansen walks past Union Rags' stable after morning exercise at Churchill Downs on Thursday.

Exercise rider Melvin Hernandez takes El Padrino for a gallop on Thursday.

Exercise rider Peter Brette takes Union Rags for a jog Thursday. At 9-2 on the morning line, Union Rags is the second choice for the Kentucky Derby on Saturday.

Trainer Bob Baffert, with the white hair, leads Bodemeister to the track Thursday morning. Bodemeister, named after Baffert's 7-year-old son, Bode, is the 4-1 morning-line favorite.

Kentucky Derby entrant Sabercat gets a cooldown bath after a morning jog Thursday. He is 30-1 on the morning line.

Trainer Todd Pletcher watches morning workouts at Churchill Downs on Thursday.

Under cover of darkness, horses fill the track in the predawn hours for their morning workouts at Churchill Downs on Wednesday.

Jockey Calvin Borel takes Kentucky Derby entrant Take Charge Indy for a morning jog Wednesday. Borel has won the Derby three times.

Exercise rider Peter Brette rides Kentucky Derby entrant Union Rags in front of exercise rider Faustino Aguilar and Dullahan during morning exercise Wednesday.

Kentucky Derby entrant Daddy Nose Best grazes Wednesday morning at Churchill Downs.

Jockey Javier Castellano takes Kentucky Derby entrant Gemologist for a gallop Wednesday. Gemologist is unbeaten in five career starts.

Jockey Julien Leparoux and owner Jamie Wyeth look at Kentucky Derby entrant Union Rags on Wednesday.

Kentucky Derby entrants Gemologist, left, and Optimizer make their way to the track for morning exercise at Churchill Downs on Wednesday.

Kentucky Derby entrant My Adonis heads to the track Wednesday morning at Churchill Downs.

Exercise riders make their way to the track for a morning workout at Churchill Downs on Tuesday. The 138th running of the event is Saturday.

Kentucky Derby entrant Bodemeister gets a bath after morning exercise at Churchill Downs on Tuesday.

Derby-winning trainers Todd Pletcher and Wayne Lukas, on horseback, talk during morning workouts Tuesday. Pletcher once served as Lukas' assistant trainer.

Exercise rider Rob Massey takes Kentucky Derby entrant Alpha for a gallop on Tuesday.

Union Rags eats after his morning exercise at Churchill Downs on Tuesday.

Exercise rider Zeke Castro walks Kentucky Derby entrant Went the Day Well after a jog at Churchill Downs on Tuesday.

An exercise rider walks a horse off the track at Churchill Downs after a morning workout in the predawn hours Tuesday.

Trainer Michael Matz, left, talks to University of Louisville football coach Charlie Strong at the Churchill Downs stables on Tuesday. Matz, who won the 2006 Derby with Barbaro, has a strong contender this year with Union Rags.

Horses enter and leave the race track in the early morning at Churchill Downs on Monday. The historic track will host the 138th Kentucky Derby on Saturday.

Trainer Larry Jones gestures as he holds the reins of Kentucky Derby hopeful Mark Valeski on Monday. Retired jockey Larry Melancon is aboard as the exercise rider. Jones saddled Hard Spun and Eight Belles to second-place finishes in the Derby but has not won the race.

Creative Cause, runner-up of the Santa Anita Derby in his last race, gets some morning exercise.

A worker holds Kentucky Derby hopeful Daddy Nose Best during a bath Monday as both are silhouetted against the morning sky.

Assistant trainer John Cisneros gallops Kentucky Derby hopeful Creative Cause on Monday.

Groom Geraldo Morales gives Kentucky Derby hopeful Daddy Nose Best a bath outside Barn 38 on Monday.

Kentucky Derby hopeful Dullahan, with exercise rider Faustino Arguilar aboard, gallops at Churchill Downs on Monday. Dullahan is coming off a win in the Blue Grass Stakes at Keeneland.

Kentucky Derby hopeful Rousing Sermon grazes outside Barn 41 at Churchill Downs on Monday, following a morning gallop.

Kentucky Derby hopeful Liaison, left, under jockey Martin Garcia, draws alongside stablemate Mile High Magic, ridden by George Alvarez, right, as they work out at Churchill Downs on Monday.

Liaison is ridden on Sunday. Trained by Bob Baffert, Liaison is likely to be a long shot. Stablemate Bodemeister might go off as the Kentucky Derby favorite.

Groom Cesai Atilano holds Kentucky Derby hopeful I'll Have Another during a morning bath after training at Churchill Downs on Sunday.

Went The Day Well jogs on Friday. He is owned by Team Valor, headed by Barry Irwin, and trained by Graham Motion. Those connections won the Derby last year with Animal Kingdom.

Union Rags, walked by Luis Aguirre, grazes after the morning excercise session on Friday. Union Rags finished second in the Breeders' Cup Juvenile at Churchill Downs last fall.

Bodemeister, under exercise rider Peter Hutton, gets an early tune-up on the track on April 24. Trained by three-time Kentucky Derby winner Bob Baffert, Bodemeister is named after Baffert's son Bode.