Saul Alvarez made the 152lb catchweight for his fight with Floyd Mayweather Jr at the MGM Grand in Las Vegas on Friday.
A boisterous crowd of around 12,000 were present for the weigh-in at the arena where the pair will meet on Saturday evening.
Much of the interest focused on how easily 'Canelo' made the weight, which is two pounds under the normal light-middleweight limit of 11st.
However, there were no problems for the 23-year-old, while Mayweather - the naturally smaller man - came in lighter at 150.5lb.
Alvarez holds both of the belts on offer - the WBC light-middleweight and WBA Super World light-middleweight titles - although Mayweather is the favourite to retain his unbeaten record.
Mayweather, who at 36 is 13 years older, has won all 44 of his fights while Alvarez has been victorious on 42 occasions with one drawn.
But the younger man says he is under no pressure to fight an opponent who is considered one of the greatest boxers of all time.
"There is no pressure whatsoever," said Canelo, who is likely to take home $10m. "It is motivating to have all of Mexico rooting for me. It truly is a pleasure to be a part of this. I appreciate all of the support for this fight.
"I want to thank my team for working hard with me. On Saturday night, I will be victorious."
Mayweather, whose earnings could top $50m when his slice of pay-per-view revenue is added to a guaranteed purse of $41m, added: "I'm not focused on the money or anything.
"I'm focused on going out there, performing well and giving the fans what they want to see - it's about excitement."
This will be the first time since 2007 that Mayweather has had more than a single fight in the same calendar year.