Today at 6:00 p.m. ET Floyd Mayweather Jr. and Manny Pacquiao will step on the scale and face off one last time ahead of Saturday's showdown at the MGM Grand in Las Vegas which has been dubbed "The Fight of the Century." Fans can watch boxing's two biggest stars weigh in live, for free, by clicking below.

This bout between stars is more than five years in the making, and almost looked to be completely dead in 2012 when Pacquiao suffered back-to-back losses to Timothy Bradley and Juan Manuel Marquez. The loss to Bradley was incredibly controversial, with most observers believing Pacquiao won handily. Against Marquez though, there was no doubt when Pacquiao was knocked unconscious and face-down. He has since recovered to win three straight fights.

Mayweather has never tasted defeat, but looked vulnerable in his first fight of 2014, a surprisingly competitive fight with brawler Marcos Maidana. Mayweather controlled the pace late, but spent much of the early and middle rounds being pushed into corners and against the ropes, as well as getting hit with chopping, overhand rights from Maidana.

In their rematch in September 2014, Maidana was defeated more soundly, but he did connect on one shot that hinted the prime version of Mayweather might be gone.

With both fighters in their late 30s, this may come down to which fighter has more of their ability intact. Mayweather's combination punching and aggression has largely disappeared; he now stands more flat-footed, relies on upper body movement to evade punches, and almost exclusively counters with pot shots.

Pacquiao has kept his quick hands and still attacks from odd angles, but hasn't knocked any opponent out since 2009. Today's weigh-in will give a glimpse of what kind of shape both fighters are in, but it's safe to assume they'll each be ready.