Floyd Mayweather Jr insisted he always planned to stay patient and leave it late against Conor McGregor after his enthralling win on Saturday.

In Mayweather's first knockout win since 2011, after starting methodically, the 40-year-old boxing legend turned it on in the later rounds and stopped McGregor in the 10th to move his undefeated career record to 50-0, breaking Rocky Marciano's all-time record.

Mayweather had promised to stop McGregor in all the preamble to the fight and the American believes he executed the perfect plan.

"That was our game plan," he said after the fight. "Our game plan was to take our time, go to him, let him shoot all his heavy shots early and then take him out at the end, down the stretch."

McGregor acquitted himself well in the early going, winning by some estimations the first three rounds, or at least two of three, but as the fight went on, the Irishman's jabs lost their bite and his lefts lost their power.

At that point, Mayweather started to tee off on McGregor, landing power shot after power shot and staggering the UFC lightweight champion in the eighth and ninth rounds before putting his night to a stop in the 10th.

"In MMA he fights 25 minutes really hard, [and] after 25 minutes, he starts to slow down," Mayweather said.

Mayweather has said multiple times this would be his last fight and he doubled down on that again after his victory.

"This was my last fight tonight ladies and gentleman, my last fight," he said to the crowd.

"For sure, tonight was my last fight. Tonight I chose the right dance partner to dance with, Conor McGregor, you're a hell of a champion and to the country of Ireland we love you guys."