Kovalev (27-0-1) retained his belts from three of the four major sanctioning bodies, the WBA, WBO and IBF, when he stopped Pascal at 1:03 of the eighth round of their scheduled 12-round light heavyweight title bout on Saturday night.
The Russian was pounding a wobbly looking Pascal in a corner when referee Luis Pabon halted the bout.
Pascal said he was about the turn the match around and win it.
"I was in difficulty, but that happens in boxing," said Pascal (29-3-1). "I never went down.
"I was coherent and in control. I think the referee didn't give me a fair shake. It's part of boxing to be hurt and then come back. I was getting ready to counterpunch and he stopped it. He's a great fighter, but I still think I can beat him."
Kovalev plans to make a mandatory defence of the IBF title against Frenchman Nadjib Mohammedi, then try to conquer the only belt missing— the WBC one held by Montreal power-puncher Adonis Stevenson. Mohammedi (38-3) fought on the undercard, stopping Lee Junior Campbell (8-2) in six rounds.
"My goal is to have all four belts in my collection," said Kovalev, who feels Pabon made the right call to stop the bout even if Pascal and the booing Bell Centre crowd didn't. "It was not an easy fight.
"His style was crazy. His punches were way wild. He showed he doesn't have a heart. He's just talking."
Pascal seemed to show enormous heart just to stay in the ring for eight rounds against a fearsome knockout artist.
Kovalev dominated the opening four rounds, but Pascal stayed on his feet and came back to win the fifth. After an even sixth, the Russian stunned Pascal with a straight right late in the seventh and continued the onslaught in the eighth.
The bout looked to be over with Pascal taking shots in a corner, but then Kovalev slipped on the wet canvas. As Pascal headed to a neutral corner, he was tripped up by Kovalev's trainer John David Jackson.
Pascal wonders if his stumble affected Pabon's decision to end the bout only moments later.
"I'm disappointed, but it's not the end of the world," said Pascal, who was stopped before the limit for the first time. "My three losses are all honourable and I'll go back to the gym, see what I need to improve and come back again."
In a co-feature, light heavyweight contender Isaac Chilemba (24-2-2) nearly pitched a shutout against Russian Vasily Lepikhin (17-1), dominating enough that one judge had him winning all 10 rounds and the other two scoring it 99-91.
Chilemba, a Malawi native living in South Africa, won the NABF title. He's ranked as the No. 2 contender by the WBC behind Eleider Alvarez and the champion Stevenson, both of Montreal.
A dreary heavyweight battle saw Ukrainian Vyacheslav Glazkov (20-0-1) pound out a 12-round unanimous decision in an elimination bout over American Steve Cunningham (28-7). Scores were 116-112 twice and 115-113. Glazkov became mandatory challenger for Wladimir Klitschko's IBF title.
Dierry Jean's first fight since leaving a rehab centre was short and sweet.
The Montreal lightweight (28-1) dropped Dominican Carlos Manuel Reyes (24-4-1) with a left to the body in the third round of a scheduled 10 round bout to claim the victory.
Jean entered rehab for alcohol and gambling addictions in November. He said he has never felt better, in and out of the ring.
Other winners were Junior Ulysse (6-0) of Montreal, Russian Dmitry Mikhaylenko (19-0) and David Theroux (6-0) of Sorel, Que.