Sergey Kovalev stopped former champion Jean Pascal in the eighth round on Saturday to retain his trio of light heavyweight world titles.

The unbeaten Russian improved to 27-0 with one draw and 24 knockouts, retaining the World Boxing Association, World Boxing Organization and International Boxing Federation crowns.

He had captured two of those belts in November with a unanimous 12-round decision over Bernard Hopkins, the first time Kovalev had to go past the eighth round.

He didn't have to go further on Saturday, pinning Pascal to the ropes with a series of blows early in the eighth.

The barrage was interrupted when the Russian went to the canvas in what was ruled a slip, giving Pascal a moment to ­regroup.

When the action resumed, however, Kovalev landed two hard rights to Pascal's head and Puerto Rican referee Luis ­Pabon stepped in, ­giving ­Kovalev the victory by

technical knockout at 1:03 of the eighth.

Haitian-born Canadian ­Pascal bitterly protested the stoppage, which was booed by the partisan crowd at the Bell Centre.

"I was still in the fight," ­insisted Pascal, who was knocked out for the first time in his career.

He suffered the first knockdown of his career in the third round, when a big right from Kovalev left him wedged ­between the ropes at the end of the round.

Pascal rallied to land some punishing blows in the fourth and fifth before Kovalev inexorably seized control.

At the time of the stoppage, all three judges had the score 68-64 for Kovalev.

"He got me a couple of good punches, but I didn't lose ­control," Kovalev said.

"I gained my control in my mind and did my job. It's boxing."

Pascal, who won the World Boxing Council crown with a unanimous 2009 decision over Romania's Adrian Diaconu and defended it three times, fell to 29-3 with one drawn and 17 knockouts.