The defending champion missed in the worst possible way, pushing his own counter at the top of the rings wide and completely missing at attempted double takeout.
After trailing the entire game, Manitoba's Jeff Stoughton suddenly had a draw for three points and win.
The veteran skip required his three sweepers to drag his stone into the rings for the 7-6 victory, indicating that Stoughton himself was taken aback by that sudden turn of events.
"I haven't digested this win," Stoughton said. "When something like that happens. It's a little surreal because you're not expecting to win.
"I thought I might have pulled the string on that last one. Thank goodness the guys got it there."
So Stoughton will play in Sunday night's championship game. He'll face the winner of the morning semifinal involving Howard and the winner of Saturday's later playoff game between Brad Gushue of Newfoundland and Labrador and Northern Ontario's Brad Jacobs.
History now favours Stoughton, a three-time Brier winner in 1996, 1999 and 2011.
In beating Ontario in the Page playoff between the top two seeds, Stoughton's record in what is called "the one-two game" improved to 4-0. He's won a Brier title every time he's been the victor in the one-two game, which is a trend Stoughton wants to continue.
"We're really going to look forward to that final," Stoughton said.
Third Jon Mead has won a pair of titles with Stoughton, second Reid Carruthers was with them in 2011 and Mark Nichols, Gushue's former third, joined the Winnipeg team prior to this season.
Howard has skipped Ontario to the Brier final six of the seven previous years and won twice, in 2007 and 2012. But his road to a seventh lengthened with a decision that generated much post-game debate.
Ontario's counter at the top of the rings partially covered Manitoba's top stone. Howard could have chosen a low-risk raise instead of a thin double. But the skip refused to second-guess himself.
"I don't regret the call," Howard stated. "I make a shot to win the game. I never dreamed I would tick my own. Lo and behold we did. I feel bad for the boys because we controlled that whole game. The bottom line is I missed."
The 50-year-old skip was more annoyed at the prospect of an 8:30 a.m. semifinal when his team was required to attend the tournament banquet Saturday evening, compounded by the fact they would also lose an hour of sleep to clocks moving ahead.
"We've got to curl the semifinal at 8:30 tomorrow, which is brilliant," Howard said with sarcasm. "Daylight Savings Time and a banquet tonight. Brilliant."
The schedules of both the Canadian men's and women's championships were back-end loaded this year. More games on the final weekend means higher ratings for the host broadcaster. Prior to this year, the semifinal was played the night before the final.
Howard finished first in the preliminary round at 10-1 followed by Stoughton at 8-3. Newfoundland and Northern Ontario also finished at 8-3, but were seeded third and fourth.
Ontario's stole a point in the ninth for a 6-4 lead. Instead of guarding and holding Manitoba to a single point, Howard aggressively tapped Manitoba off the button. Stoughton needed a piece of it for one and slid too far.
Ontario couldn't clear Manitoba counters in the eighth and Howard was forced to draw for a point and a 5-4 lead.
Howard blanked the seventh. With a counter biting the back of the rings in the seventh end, Howard lost a chance for two when his shooter stayed out of the rings while clearing two Manitoba stones on the top edge of the rings.
Stoughton got his first deuce of the game in the sixth end to tie it 4-4. He squeezed past a guard to execute a tap for two.
Ontario took a 4-2 lead in five. Stoughton attempted an angle raise double takeout, but left one Ontario counter. Howard drew the four-foot rings for the deuce.
Stoughton was held to one point in the third, but stole a single in the fourth when Howard missed an angle raise. As the No. 1 playoff seed, Howard had hammer to start the game. After blanking the first end, Howard hit for two.