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. Continued...