Hometown favourite Lucian Bute had warned for a week that Irishman Brian Magee would be a tougher opponent than people thought.
He was right.
The 35-year-old Magee took punches, picked himself up off the canvas three times and kept fighting until Bute dropped him once and for all with an uppercut 2:04 into the 10th round in Montreal.
"It was not an easy fight," said Bute, who improved to 28-0. "I hit him early but he has a very hard head.
"I hit him and hit him and he kept advancing."
Bute felled Magee (34-4-1) with a body shot in the sixth and had him down twice in the seventh, once on a low blow that wasn't counted and again with a body shot.
Nearly all among the 12,219 at the Bell Centre thought it was another body shot that dropped him in the 10th, but replays showed it to be a subtle but thundering uppercut to the chin.
"I thought he'd go to the body again," said Magee. "I didn't think it would be an upper cut.
"It's not so bad having a loss on your record against the best in the world. He's a great champion. I gave it everything. He's probably the best guy I've ever been in with. Very solid, compact, smart."
The European champion, a loser in his first shot at a world title, said he now hopes to try for the WBA belt.
Meanwhile, the Montreal fighter defended the IBF belt he won in 2007 for the seventh time. Magee failed to go the distance for only the second time in his career.
A bout that took place almost entirely in the centre of the ring saw both fighters try to establish the jab. The first five rounds were mostly even, but there was a sense that the taller, quicker Bute had another move up his sleeve.
It came out in the sixth as a quick left to the midsection put Magee down. The same happened in the seventh and then it was only a matter of time for the knockout blow to come.
As Magee winced and fell in the 10th, Chicago referee Pete Podgorski right away signalled the end of the fight.
In the co-feature, hard-hitting Pier Olivier Cote of Quebec City stopped Michael Lozada of Mexico with three knockdowns in the first round to win his light welterweight bout.
A crushing right to the ear at 2:50 of the first gave Cote (15-0) an impressive victory over Lozada (37-8-1) and a second straight one-round win.
"I thought he'd be more aggressive, but I saw he was backing up," said Cote, one of Canada's most promising young fighters along with middleweight David Lemieux. "I got him with a shot, he lost his legs and it was pretty much over from that point."
The victory assured Cote of a spot on the undercard of the Manny Pacquiao-Shane Mosley super-fight May 7 in Las Vegas against an as-yet unannounced opponent. However, Cote said his top priority to is fight for a North American title and would take that over a non-title bout, even in Vegas.
The 26-year-old Cote was born in Cali, Colombia, but at 18-months-old was adopted by Rejean Cote and Christiane Pleau of Charlesbourg, Que.
He started boxing at 20 and was Canadian amateur champion within two years. He turned pro in 2008 and has impressed many with his devastating right hand shots.
Carl Moretti of promoter Top Rank this week called Cote a "special talent."
In another co-feature, Armenian-born Vanes Martirosyan (29-0) dropped Bladimir Hernandez (18-5) of Mexico just 57 seconds into the second round of a scheduled eight-round light middleweight bout.
Martirosyan was using the fight to shake off rust after a sub-par win by decision in his last appearance in June against Joe Greene.
Bute, a 31-year-old Romanian-born Canadian, was the heavy favourite over the 35-year-old European champion who was in his first world title fight.
At ringside was former world champ Mikkel Kessler of Denmark, a likely future opponent for Bute once he recovers from the eye injury that forced him out of Showtime's Super Six tournament of top super-middleweights.
Bute is expected to take on the Super Six winner early next year if he keeps winning.
On the undercard, Benoit Gaudet (24-2) of Drummondville, Que., scored a unanimous decision over Adrian Verdugo (14-4-1) of Mexico when the super featherweight bout went to the scorecards after six rounds due to an accidental head butt.
Viorel Simeon (13-0), a 29-year-old Romanian, made an entertaining debut with Montreal promoter InterBox. The rapid-fire puncher got up twice from the canvas in the second round to earn a split decision victory over Pedro Navarrete (25-11-3) of Mexico.
Newcomer Schiller Hyppolite (1-0) knocked down journeyman Patrick Tessier (4-13-2) with an overhand right in the second and got the four-round unanimous decision in a light heavyweight bout between local fighters.
Sebastien Gauthier (20-2) of St. Jerome, Que., knocked out Jovanny Soto-Ramirez (29-13-1) of Mexico in the second round of a bantamweight bout.
Light heayweight Colin McFadden of Oshawa, Ont., was scheduled to make his pro debut but it was cancelled when opponent Mike Bucannan didn't pass the pre-fight physical.