Conor McGregor has put to shame Floyd Mayweather's suggestion that he was struggling to make fight weight by comfortably making the mark for the two combat sport superstars' fight in Las Vegas on Sunday.

The American had questioned his Irish foe's ability to hit under the 154 pound (69.85kg) limit after his "spies" had informed him that McGregor was battling a tough weight cut.

Mayweather came in well under the maximum, weighing in at 149.5 pounds (67.82).

McGregor revealed on stage that he expects to be around 170 pounds (77.11kg) come fight time and ridiculed Mayweather for looking drawn out.

The brash Irishman is confident he will shock the boxing world and walk right through the 49-0 boxing kingpin.

"I'll stomp my foot right in the centre of that ring. I won't go nowhere other than the centre of that ring. So let's see who can take it," McGregor said.

"He's over there twiddling his thumbs, twitching away. I see a man afraid."

For his part 'Money' has promised the fight won't last long, with McGregor being in for a rough night.

"I've been here before. I know what it takes when it's a fight of this magnitude. Weight doesn't win fights. Fighting wins fights," he said.

"It won't go the distance. Mark my words. I'm not really worried about the scale or [that it's his] last time. This will be Conor McGregor's last fight also."

Floyd Mayweather vs. Conor McGregor is a 12-round super welterweight matchup that pits the legendary boxer Mayweather against the all-time MMA great McGregor in the main event of an unprecedented four-fight pay-per-view boxing event.  Mayweather vs. McGregor will take place Saturday, Aug. 26 at 9 p.m. ET/6 p.m. PT at T-Mobile Arena in Las Vegas.  The event is produced and distributed live by SHOWTIME PPV, promoted by Mayweather Promotions and sponsored by Corona. Coverage of the Prelims will begin on FOX and FOX Deportes at 6 p.m. ET/3 p.m. PT.