Victor Ortiz took the first round to feel out opponent Vivian Harris and then unloaded.

Ortiz (28-2-1, 22 KOs) put Harris (29-5-1, 19 KOs) down three times in the second round to set up the knockout in the third on the Shane Mosley-Sergio Mora card Saturday at Staples Center.

The Ventura, Calif. resident landed a right-hook and then a quick right uppercut to end it 45 seconds into the round. Referee Raul Caiz waved off the fight the moment Harris hit the canvas.

Harris, from Brooklyn, N.Y., was coming off a knockout loss to Lucas Matthysse in February.