Golovkin vs. Rubio: Live Round-by-Round Results and Highlights

Golovkin (31-0, 28 KO) dropped Rubio with a massive overhand left near the ropes, and the Mexican challenger made no attempt to rise from the mat, being counted out by referee Jack Reiss.

With the win, Golovkin retained his WBA Middleweight Championship and captured the WBC's interim 160-pound belt, making him the No. 1 contender to lineal middleweight champion Miguel Cotto.

Golovkin, who was making his West Coast debut, packed over 9,000 fans into the StubHub Center, a new record for the venue, proving his drawing power.

The Kazakh bomber has struggled to attract high-quality opponents during his rise to the top of the middleweight division, and Rubio (59-7-1, 51 KO) was expected to provide him with at least a few rounds.

Instead, he became just the latest victim of a fighter on the bullet train toward superstardom, Bleacherreport.com reports.