Trainer Bob Baffert has no regrets about running American Pharoah in the Travers Stakes despite the Triple Crown winner's defeat.

Until Saturday (Sunday AEST) American Pharoah had not lost a race since his debut last August at Del Mar.

He had reeled off eight straight wins, seven at Grade One level including his historic sweep of the Kentucky Derby, Preakness and Belmont Stakes.

In the Travers, his first try at 1-1/4 miles (2000m) since the Derby, American Pharoah was pressed from the gate to the top of the straight by Frosted before getting clear. But he but didn't have enough left to hold off the late-running Keen Ice.

The question now is when, or if, American Pharoah will run again.

Owner Ahmed Zayat said immediately following the Travers the horse would be retired at the first hint of regression.

A day later, Baffert said he had not seen any sign of that and would prefer to train him up to the $5 million Breeders' Cup Classic on October 31 at Keeneland, his last scheduled start before going to stud.

"He looks great today," Baffert said. "He could come back and freshen up and run.

"I don't think he tailed off. I think he just didn't bring his 'A' game. If you look at him, he still looks pretty healthy. He doesn't look like a tired horse."

"If I had to do it again, I would have brought him here. I'm glad I brought him.

"I think racing needed something like this," Baffert said. "It's amazing, what he's done for racing.

"Everybody in town afterward, when they saw me they said, 'We're sorry. We feel so bad for you, Bob, but thanks for bringing that horse.' It almost ended well. We almost pulled it off."