Former boxing champ Ray Mancini says Canelo Alvarez ain't like Roger Clemens, Barry Bonds, Mark McGwireand Ben Johnson ... cause unlike those guys, PED's won't hurt Alvarez's legacy.
Canelo is set to take on GGG Saturday in the biggest fight of the year ... but there are some people who think that an Alvarez win would be tainted by his positive drug tests from earlier this year.
You might remember, the fight was postponed because the Mexican champ twice tested dirty for Clenbuterol in his bloodstream .