Irish trainer Aidan O'Brien liked the look of So You Think, his 5-1 challenger in Saturday's $US5 million Breeders' Cup Classic, after checking out the horse at the barn on Thursday.Uncle Mo is 5-2 favourite in the 1-1/4-mile (2000m) Classic, the top event in the two-day card of 16 races, with filly Havre de Grace at 3-1 and O'Brien's horse edging Flat Out (6-1) among the field of 12 in the feature."I'm very happy with the horse," O'Brien said."He's a very relaxed horse in his races and sometime

Irish trainer Aidan O'Brien liked the look of So You Think, his 5-1 challenger in Saturday's $US5 million Breeders' Cup Classic, after checking out the horse at the barn on Thursday.

Uncle Mo is 5-2 favourite in the 1-1/4-mile (2000m) Classic, the top event in the two-day card of 16 races, with filly Havre de Grace at 3-1 and O'Brien's horse edging Flat Out (6-1) among the field of 12 in the feature.

"I'm very happy with the horse," O'Brien said.

"He's a very relaxed horse in his races and sometimes can become too relaxed so we put a pair of blinkers on him just to try and make him concentrate a little bit more."

So You Think will run with blinkers for the first time in two years since a race at Flemington in Australia.

The showdown could decide the season's top three-year-old, with the US Triple Crown races producing three different winners.

Uncle Mo, unbeaten as a two-year-old in 2010 and winner of last year's Breeders' Cup Juvenile at Churchill Downs, was pulled out of the Kentucky Derby in May with an illness later diagnosed as a life-threatening liver ailment.

The colt returned to racing in August and along with stablemate Stay Thirsty galloped 1-1/4 miles on Thursday.

"If Stay Thirsty or Uncle Mo were to win, they would make a very good case for themselves," trainer Todd Pletcher said of the Horse of the Year battle.

"It has sort of been one of those years when some horses have had a hard time putting together a lot of victories, so this one's going to carry monumental weight."

Trainer Bob Baffert's four-year-old gelding Game On Dude, the winner of the Santa Anita Handicap who is at 10-1, galloped an easy mile (1600m).

"He's a 'Plain Jane,'" Baffert said.

"He just goes around there nice and easy and does his job. He's a really cool customer. He just gets around there like it's no big deal."

Scooter Dickey, Flat Out's 70-year-old trainer, had his five-year-old gallop 1-1/4 miles on Thursday and expressed hopes for the horse's chances in a wide-open field.

"It's shaping up to be a really good race," he said.

"None of us are really shadowing the other. We've all been beat by one or another and they're all running real good right now."