LAS VEGAS (AP) — 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 retained his piece of the middleweight title, but it was not without some nervous moments for his fans who packed the new T-Mobile Arena on the Las Vegas Strip. Khan was more than holding his own in a tactical fight when the right hand suddenly ended it.

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.