CARSON, Calif. — Andrzej Fonfara knocked down Julio Cesar Chavez Jr. in the ninth round and won after the bell Saturday night when the referee stopped it.

Fonfara (26-4, 15 KOs) landed big shots all night at the outdoor StubHub Center ring, and his left hand in the ninth knocked down Chavez (48-2) for the first time in the boxing scion's career.

Chavez's corner stopped the fight after nine rounds, and the crowd threw beer while roaring its displeasure.

"I think I [was winning] the fight," said Chavez [at the time of the TKO he was down significantly on all three cards]. "My strategy is to work the body but the guy is too heavy for me. He's a good fighter. I want a rematch at 170."

Fonfara was penalized a point for using his shoulder in the seventh, but appeared to be in control before the stoppage.

The win was his second straight since a competitive loss to light heavyweight champion Adonis Stevenson.

The enigmatic Chavez hadn't fought since March 2013, when he convincingly won a rematch with Bryan Vera.