INGLEWOOD, Calif. – Oleksandr Usyk stopped Thabiso Mchunu at 1:53 of the ninth round on the Bernard Hopkins-Joe Smith Jr. card Saturday at the Forum.

Usyk (11-0, 10 knockouts) struggled with Mchunu (17-3, 11 KOs) in the first several rounds, apparently having difficulty coping with the South African’s awkward style and possibly his diminutive stature.

However, by the fourth round, the 6-foot-3 Ukrainian had solved the puzzle, picked up his punching activity and wore Mchunu down.

Usyk put Mchunu down with a left uppercut followed by a glancing right to the head in the sixth round, although Mchunu didn’t appear to be hurt. In the final round, Mchunu, evidently feeling beat up by that point, twice took a knee after absorbing a series of hard punches.

The fight was stopped after the second knockdown of that round, as Mchunu was clearly finished.

Usyk, the 2012 Olympic heavyweight gold medalist, was defending the WBO cruiserweight title he won by outpointing Krzysztof Glowacki on Sept. 17 in Poland.