Canelo Alvarez needed only one big right hand to turn a close fight into a smashing knockout.

Struggling with Amir Khan’s speed, Alvarez unleashed a long right hand that send Khan backward on the canvas, where referee Kenny Bayless didn’t even bother to count him out at 2:37 of the sixth round.

Alvarez went and kneeled before an unconscious Khan, then went over and motioned to Gennady Golovkin, who was ringside, to join him in the ring for a fight.

"I invited him to come to the ring. Like we say in Mexico 'we don't f*** around.' I don't fear anyone; we don't come to play in this sport. I fear no one in this sport. Right now I will put on the gloves again and fight him."

It may not take too long for the fight boxing fans have been waiting for to happen, though the weight could be an issue. Alvarez wants the bout to be less than the 160-pound middleweight limit, while Golovkin, who holds his own piece of the middleweight crown, vows to fight at his best weight.

“I am old school,” Golovkin said just before the fight. “Middleweight is 160. I respect the sport of boxing.”

Khan, a 6-1 underdog, had vowed to use his speed to confound Alvarez and his plan seemed to be working. He fought in spurts, landing combinations and seemingly frustrating Alvarez with his movement.

But a right hand that came out of nowhere landed flush against Khan’s chin, and he was out before he hit the canvas.

Alvarez was making the first defense of the WBC title he won from Miguel Cotto in November, though the fight was fought at a catch weight of 155 pounds. The WBC has said it will take the tile from Alvarez if he does not begin talks for a fight with Golovkin within 15 days.