0745 GMT April 08, 2020
The Kazakhstan-born, California-trained middleweight secured his 18th consecutive stoppage victory, in his 12th title defense, with a crushing left hand blow just 79 seconds into the second round.
"I liked the fight," Golovkin said. "Rubio, he does not step back. He is a good fighter. I respect him. It was a very hard punch."
Golovkin battered Rubio throughout, landing 28 power punches in just over four minutes, and hurt the Mexican early in the second round with a right hand and a left uppercut before a barrage of blows sent him crashing to the canvas, skysports.com reported.
"I felt I hurt him with the left hand, and the uppercut was when he was very badly hurt," Golovkin added.
"I knew I had him. I was happy he came forward. He fought Mexican style, and he tried to hurt me, but my power was too much for him."
Rubio, who briefly complained that the knockout punch was illegal, said, "Gennady is a great champion. He hit me hard, but it's not the hardest I've been hit. I came to fight, to put on a good show. I got up, but the referee decided to stop it."
Golovkin won Rubio's WBC interim belt, which means the winner of WBC champion Miguel Cotto's upcoming bout with Canelo Alvarez must either fight Golovkin or vacate the title.
He has trained in Southern California with Abel Sanchez for the past four years and the Germany-based fighter is now contemplating a full-time move to Los Angeles.
After starting his American career with five fights on the East Coast, he debuted in California with the Los Angeles Dodgers' logo on his left hip.
"He'll fight anyone, whoever we can get in the ring," promoter Tom Loeffler said.
"He's collecting belts. He wants to show he's a super champion, and 2015 will be a huge year for him."