who has given mayweather his toughest tests

[rightsideup]

Oscar for one who else? Also who else from another era would trouble him or down right defeat him?

[jas]

Castillo. .

[MDPopescu]

Castillo. .

It was an accident... The guy had his hand broken early.

[Sugar Adam Ali]

Castillo by far gave him his toughest fight..

then cotto

then oscar

Then Chavez

then augustus

Shane and corley get honorable mentions for tagging floyd, and making him overcome adversity

[jas]

Floyd said Augustus was his toughest fight

[BKM-2010]

Gonna have to go with Cotto imo. He didn't just make Mayweather go all out and use "plan B and C" but also the bloody nose and constant left jab to his nostrils gave him a tough time, and that's different than a broken hand because your opponent's hand being broken is not really damage that you did to him.

[way2strong]

juddah made fraud earn his victory