Trainer Bob Baffert has admitted Arrogate is racing below par after the world's highest-ranked and horse finished second to his stablemate Collected in the Grade One Pacific Classic at Del Mar.

"He ran a good race, but we expect to see something else," Baffert said.

"I feel like my older son got beat by my younger son."

The odds-on favourite's defeat came after his distant fourth last month behind Accelerate who finished third on Sunday (AEST).

Jockey Mike Smith said although Arrogate finished strongly, he was still not at his best.

"Better than the last one, but it's not good enough," Smith said.

"He's not running his A race. I'm not even sure he's running his B race, to be honest with you, and he's still only getting beat a little bit."

Arrogate travelled in third place most of the way and passed Accelerate in the straight but was half a length short of Collected at the post.

Winx, rated second in the world behind Arrogate, returned with a last-to-first win in the Group Two Warwick Stakes at Randwick on Saturday.

But she will not go past him with his ranking of 134 earned in the Dubai World Cup in March standing as his high point this year.