By Keith Idec

Canelo Alvarez has never been knocked out in 10 years as a professional prizefighter and has displayed a sturdy chin since surviving some trouble against Jose Cotto in a fight Alvarez eventually won easily 5½ years ago.

Trainer Freddie Roach explained Wednesday why he is convinced that’ll change when Alvarez meets Miguel Cotto, whom Roach predicted will win by knockout in their middleweight showdown Nov. 21 in Las Vegas (HBO Pay-Per-View; $59.99-$69.99).

“[This is] a different caliber of fighter,” Roach, Cotto’s trainer, said during a conference call. “I think this is the best fighter [Alvarez] has ever fought. I think he’s been [fighting] hand-picked opponents. You know, Mayweather is a tough fighter, but not a big puncher."

"And this is the first heavy puncher he’s going against, and Miguel’s looked great in his last three fights. His punching power is improving, he’s using every bit of his body weight to do that, and that’s something we’re working on and he’s punching very well. And I feel that this guy gets hit too much and I think Miguel will knock him out somewhere along the way.”

Puerto Rico’s Cotto (40-4, 33 KOs) and Mexico’s Alvarez (45-1-1, 32 KOs) will fight for Cotto’s WBC and The Ring middleweight titles at Mandalay Bay Events Center. The 25-year-old Alvarez is a 3-1 favorite over the 35-year-old Cotto, who has been stopped twice since making his pro debut in February 2001.

Keith Idec covers boxing for The Record and Herald News, of Woodland Park, N.J., and BoxingScene.com. He can be reached on Twitter @Idecboxing.