Liberal MP Justin Trudeau beat Conservative Senator Patrick Brazeau in their charity boxing match in Ottawa Saturday night.

The referee stopped the fight before the third round ended.

Liberal Leader Bob Rae tweeted his congratulations moments after the bout ended: "Justin Trudeau - great win all for a good cause!!"

Trudeau and Brazeau had a sell-out crowd for their bout, which benefitted the Ottawa Regional Cancer Foundation.

The three-round headliner at the capital's Hampton Inn followed a red-carpet event.

But it was more than just a tough fight night for Trudeau as his maternal grandmother, Kathleen Sinclair, died Saturday in a British Columbia nursing home at age 92. Her daughter Margaret married former prime minister Pierre Trudeau in 1971.

Hours before the bout, Trudeau told reporters that he was "feeling good."

"I've done what I had to do to get to this point," he said. "I'm confident with it."

Brazeau could be seen outside the Hampton Inn alone, getting pumped up for the fight by listening to his iPod.

The two men, both of whom are known for their full heads of hair, have agreed that the loser will have his hair cut in the foyer of the House of Commons. But Brazeau will not just have to shed his long ponytail -- the two men also agreed the loser will wear a jersey bearing the winner's party logo for a week.

Both fighters ramped up the trash talk this week during a weigh in and during an appearance on CTV's Canada AM Friday.

"We'll see which of us has to get the haircut of shame," Trudeau said as Brazeau sat beside him in Ottawa smiling coyly during the interview.

Bookies placed 3-1 odds against Trudeau coming out victorious. Brazeau, who had been training hard and has a black belt in karate, certainly made it clear publicly he would have been happy with a Trudeau knockout.

Pundits suggested the wiry Trudeau didn't need to win the match, but just survive the event without humiliation to make his point. He's one Liberal politician Conservatives love to hate.

Trudeau said he had been at the gym three times a week for the past six months, and has several years of boxing experience to back him up.

But at a lanky six-foot-two and 175 pounds, experts thought he would have his work cut out for him against Brazeau, who stands at a much stockier five-foot-eleven and 183 pounds.

Trudeau attempted to get Defence Minister Peter MacKay and Calgary MP Rob Anders to accept the fight before settling on Brazeau.

"I was sort of surprised it was as difficult as it was to find a Conservative across the aisle in the House not willing to punch me in the face," Trudeau said. "I suspected more of them would have wanted to."