Pavlik bounced back from his defeat by Hopkins last October
Kelly Pavlik retained his WBC and WBO middleweight titles when Mexican Marco Antonio Rubio was pulled out after nine rounds by his corner on Saturday.
Pavlik, fighting in his home town of Youngstown, Ohio, went into the bout following a defeat by Bernard Hopkins in a non-title contest last October.
But he dominated Rubio from the start, hurting him in the eighth round and battering him throughout the ninth.
"There's no place like home," said the 26-year-old Pavlik.
"There was a lot of pressure on me for this fight but it's great to bounce back in my hometown.
"I feel great. I put that loss (to Hopkins) behind me. I give a lot of credit to (Rubio). He's a lot tougher than I expected."
It was Pavlik's second successful defence of his WBC and WBO belts, which he won with a technical knock-out of Jermain Taylor in September 2007.
The 28-year-old Rubio had won nine straight fights since moving up from junior middleweight but he was clearly outclassed in his first challenge for a major title.
"We kept him going backwards," Pavlik's trainer Jack Loew said. "We saw in the tape that Rubio had trouble fighting backwards. That was our plan and Kelly executed it perfectly."
Pavlik landed a devastating left midway through the opening round and often backed Rubio into his own corner, landing a series of body shots.
Rubio rallied in the sixth round, landing two left hooks and standing toe-to-toe with Pavlik at the end of the round.
But Pavlik shook the Mexican again with a big right hand near the end of the eighth round and boxed him into a corner early in the ninth.
Rubio's team decided it had seen enough, telling referee Frank Garza to stop the carnage with their fighter sitting on his stool.