The veteran Cuban launched an overhand left in the sixth round which badly hurt Martin and caused his demise.

The earliest exchanges had all gone the way of Martin, who had sent Ortiz tumbling to the canvas twice.

A sneaky right hand from Martin, the former IBF champion whose loss to Anthony Joshua in 2016 means he has the second-shortest heavyweight title reign in history, shocked and floored Ortiz in the first round.

The battle of southpaw jabs was being won by Martin who, in the fourth round, timed a shot which knocked Ortiz over again.

But Ortiz exploded into life in the sixth round when his powerful left hand cracked Martin flush in the face.

Martin immediately looked out on his feet.

A series of follow-up shots from Ortiz crumpled Martin down - as he fell, his glove became twisted in the ropes and required the referee to untangle him.

Somehow Martin came back for more and valiantly continued until Ortiz's heavy shots sent him down for a second time, and the referee called a halt.

The 42-year-old Ortiz delivered a reminder that he remains a threat to the upper echelons of the heavyweight division.

This fight was an IBF eliminator - Martin was previously ranked at No 1 by the governing body.

Ortiz has only lost twice to Deontay Wilder in 37 career fights but has now positioned himself to potentially become the mandatory challenger for the belt that Oleksandr Usyk is set to defend against Anthony Joshua.