Former welterweight champion Andre Berto on Wednesday will undergo surgery in Los Angeles to repair a torn tendon in his right shoulder sustained during his 12th-round technical-knockout loss to Jesus Soto Karass on July 27 in San Antonio.

Berto said he suffered the injury in the second round.

“I threw a punch in the second round and when Soto Karass blocked it, my right upper arm connected with his and it felt like fire shot through my arm,” Berto said. “I had no power at all in that right arm and couldn’t hold it up to defend myself. I kept trying to use it, but midway through the fight, I realized I couldn’t and just tried to work my left hand and throw jabs.”

Berto said out of sheer instinct he used his right, and he intimated the pain was excruciating.

“I could see that Soto Karass and the referee (Jon Schorle) heard me (yelling from the pain), and the referee and doctor kept coming to the corner between rounds to check on the injury, but there was no way I was going to quit,” Berto said.

Berto, 29, is from Winter Haven, Fla. He has now lost three of his past four bouts.