Casino Drive has a small bruise on his left hind hoof and did not go to track this morning in advance of tomorrow's Belmont Stakes.

Casino Drive's racing manager, Nobutaka Tada, said he still expected the horse to race in the third leg of the Triple Crown. Trainers and staff found the bruise during a walk at 5 this morning, he said.

"If he stays like this, there is no reason to stop him," Tada said outside Casino Drive's barn late this morning.

Casino Drive is seen as the biggest challenger for Big Brown, which is trying to win the Triple Crown.

Tada said Casino Drive will be monitored closely and he did not rule out scratching the horse from the race.

"It all depends on how he moves tomorrow morning," Tada said. "This morning we are not 100 percent happy with movement in his hind leg. We didn't like the way he walked. He has a good appetite and he is drinking."

The first sign of trouble came earlier this morning when Big Brown's trainer, Rick Dutrow, said he heard of problems with Casino Drive.

"I had people calling me last night that he is going to scratch," Dutrow said at his morning news conference. "I just think he's got issues. I heard it again this morning."

Big Brown has his own hoof issues. Ian McKinlay, the hoof specialist treating Big Brown, planned to seal the crack in a hoof this afternoon.

"As far as that crack goes, I'll guarantee that," McKinlay said when asked if it the treatment will work.

Contact staff writer Mike Jensen at 215-854-4489 or mjensen@phillynews.com