Mayweather re-established his position at the top of the game last May with a unanimous decision win over Robert Guerrero. He has been world champion at 130, 135, 140, 147 and 154 pounds, and is 5/14 favourite to win against Alvarez.
Tale of the tape:
Age: 36, born February 24, 1977.
Birthplace: Grand Rapids, Michigan, USA. Now lives Las Vegas, Nevada.
Saturday's bout and its billing as the richest fight in history will see Floyd Mayweather attempt to unify his WBA light middleweight title against WBC 154-pound champion Saul 'Canelo' Alvarez at the MGM Grand Garden Arena in Las Vegas.
Pound for pound number one at 36, Mayweather is back in the ring for the second time in five months.
Canelo turned pro at 15 and wins with a hard-hitting style and a powerful body attack.
Alvarez signed with Golden Boy Promotions in 2010, and his impressive unbeaten record of 42, no losses and one draw rivals that of Mayweather on 44 wins, no losses and 26 Knock Outs.
This is my chance to prove once and for all that I'm the best in the division.
I can win the WBC title and will have held three of the four belts in the light-welterweight division, so it's time to move up to 147lbs.
I just think there are more challenges out there for me in that division.
I want to be in big world title fights and in big fights with the likes of Mayweather. To do that, I need to be up in that division.
Watching Mayweather's last fight (a points win against Miguel Cotto), coupled with the way I've been training, I think I'm ready.
One of the reasons I want to move up to 147lbs is to fight Mayweather and it's not about the money, it's about me knowing I can beat the guy and be the next guy at the top, the next pound for pound champion.
– Amir Khan told Press Association Sport
Floyd Mayweather is currently serving a prison sentence for domestic violence and Khan will be waiting when he is released in a few weeks' time.
Floyd Mayweather Jr added the WBA Super World light-middleweight title to his tally with a unanimous points victory over Miguel Cotto in Las Vegas overnight.
Mayweather won by margins of 118-110 and 117-111 (twice) on the judges' scorecards to preserve his unblemished 43-fight record.
Attentions will once again turn towards the prospect pairing Mayweather with pound-for-pound rival Manny Pacquiao, but the 35-year-old American must first serve a three-month prison sentence after pleading guilty to a domestic violence charge.