Nigeria, Feb. 17 -- Nigerian heavyweight contender Efe Ajagba has fired a thunderous warning across the division, demanding bouts with top-10-and even top-five opponents after defeating former IBF champion Charles Martin with a ruthless fourth-round knockout in Las Vegas on Sunday night.

Ajagba, 31, ranked eighth by The Ring, delivered a punishing display at the UFC Apex, flooring Martin twice before referee Thomas Taylor halted the contest at 1:11 of the fourth round.

The finish was as dramatic as it was decisive. Ajagba had been briefly shaken late in the third round when Martin clipped him with a left that momentarily buckled his knees. But the Nigerian responded instantly, detonating a savage right hand that sent the former champion...