Miguel Cotto returned to the ring after an absence of almost two years to claim the vacant WBO world super-welterweight title by outpointing Yoshihiro Kamegai in Carson.
Cotto (41-5, 33KOs) had not fought since being outpointed by Saul Alvarez for the vacant WBC world middleweight title back in November, 2015.
But the 36-year-old showed little signs of ring rust, being happy to trade from the first bell and using all his experience to take a unaminous 120-108, 119-109, 118-110 decision on the cards.
Cotto - a six-time former world champion and the first boxer from Puerto Rico to win world titles in four weight classes - still intends to fight again in December before retiring at the end of the year.
"I think I did my best and I'm happy with my performance," said Cotto.
"(Kamegai) is a tough fighter. By the fifth or sixth round, I knew I was not going to be able to stop him.
"I will do it (retire). I'm 36 now. I'll be 37 on October 29. I've done too much over the years. I think it's time. One more in December and that is all."
On the undercard in California, Rey Vargas (30-0, 22KOs) made the first defence of his WBC world super-bantamweight title with a unanimous 118-110, 118-110, 115-113 points win over Ronnie Rios.
Mexican Vargas had won the vacant title back in February when he outpointed Doncaster's Gavin McDonnell.