Barely.

Whittaker drilled Rivera with a left hook as he charged forward and dropped him very early in the second round. Rivera got up, but referee Michael Griffin waved an end to their scheduled 10-round light heavyweight fight 27 seconds in on the Xander Zayas-Jaron Ennis undercard at Barclays Center in Brooklyn.

Whittaker (12-0-1, 9 KOs) also dropped Rivera toward the end of the first round, though it looked like his right hand landed on the back of his head.

Rivera (27-3, 20 KOs), of Hartford, Connecticut, had not been knocked out before the brash British contender stopped him.

Whittaker, 29, has knocked out four straight opponents since the odd ending to his first fight with Liam Cameron in October 2024.

Cameron and Whittaker were engaged in a competitive fight when they became entangled and went over the top rope and out of the ring together. Whittaker suffered ankle and neck injuries from his fall, couldn’t continue and their bout resulted in a six-round split technical draw.

The West Bromwich, England, native knocked out Cameron in the second round of their immediate rematch and Benjamin Gavazi and Braian Suarez in the first round of his two subsequent bouts before he faced Rivera.