Boxers Sergey Kovalev (left) of Russia and Saul "Canelo" Alvarez of Mexico fight in their WBO light heavyweight title bout, at the MGM Grand Garden Arena. Photo: IC

Saul "Canelo" Alvarez knocked out Sergey Kovalev with a vicious combination in the 11th round to win the WBO light heavyweight title on Saturday, moving up two weight classes to become a four-division champ.

The 29-year-old superstar caught Russia's Kovalev with a left hook-right hand combination that sent the former champion almost crashing through the ropes near the end of the 11th round at the MGM Grand Garden Arena in Las Vegas.

"This is just one step in my history," Alvarez said. "Be patient because Canelo will make history. It's a guarantee."

"Krusher" Kovalev was officially knocked out at 2:15 of the 11th and stayed down for some time while being attended to by his corner and the doctor.

It was one of the most devastating knockouts of the brilliant career of boxing's biggest star Alvarez, who was fighting in the 175 pound division for the first time. 

The fight had been close throughout with Kovalev (34-4-1, 29 KOs) winning most of the early rounds by using a steady jab to keep the burly Alvarez at a distance. Alvarez was ahead 96-94, 96-94, 95-95 on the scorecards.

Alvarez (53-1-2, 36 KOs) became just the fourth boxer in history to win a junior middleweight world title and one at light heavyweight, a spread of 21 pounds (154 to 175). The other three are Sugar Ray Leonard, Thomas Hearns and Mike McCallum. Alvarez is also the second fighter from Mexico to win a light heavyweight belt, joining Julio Gonzalez who did it in 2003 and 2004.

Despite giving up a size and reach advantage, Alvarez's best punch throughout was the left hook which he used in the 11th to initially send Kovalev staggering backwards to the ropes. As a defenseless Kovalev was going down, Alvarez then landed a vicious right hand to the face that knocked the champion out cold. 

"It was a very close fight. He was defensive, closing up his guard. All he was doing was establishing his points, getting points. But we knew it was coming and everything came out the way we had planned," Alvarez said. 

This was Alvarez's first fight since a unanimous decision over Daniel Jacobs in May. 

Alvarez is now riding a four-fight winning streak with his lone blemish being a majority draw against Gennady Golovkin in their first of two bouts.

He sought out Kovalev to add another belt to his impressive collection which includes titles at junior middleweight, middleweight and super middleweight.