Bob Baffert’s outstanding colt American Pharoah is out of this weekend’s Breeders' Cup Juvenile at Santa Anita.

The Zayat Stables homebred Pioneerof the Nile colt was coming off back-to-back Group One victories in the FrontRunner Stakes and the Del Mar Futurity.

Owner Ahmed Zayat said via Twitter: "American Pharoah will be scratched; was off this morning. Horse comes first. Vets can't find anything visually wrong, X-rays are clean."

Baffert said American Pharoah was withdrawn from the BC Juvenile because of what could be a "deep bruise" in his left front foot.

He said it was discovered after the colt's workout on Monday.

"It was a great work but he wasn't 100% afterward," Baffert said.

"I wasn't really comfortable with it, so we X-rayed him and did an ultrasound. Everything was clean, so we're hoping it's just a bruise.

"He's too valuable and we don't want to risk it. I've had horses withdrawn before races but this one has to be the most disappointing.

“We all saw how he was training and he's something special; I haven't had a colt like this in a long time.

"I think he's going to be OK but it's a tough pill to swallow. He had the perfect draw but I would gladly trade a perfect draw for him to be 100% and race."

Baffert said American Pharoah will undergo additional testing in the coming days.

"We have to pinpoint exactly what it is," he said.

"It's not soft tissue, it's not bone, but there's something there so we'll just have to deal with it with some more diagnostic evaluation."