Calvert gave up a steal of one to Comeau in the fifth end when his last-rock hit attempt to score three overcurled.
But Calvert, who finished the game shooting 89 per cent, tapped for a game-tying deuce in the sixth, stole one more in the seventh and finished off with the 10th-end deuce for the win.
"They had all the momentum after the steal and we kind of got it back again right away," said Calvert, whose team moved into sole possession of first place in the eight-team championship round with a 7-1 record while New Brunswick dropped to 6-2.
"We're playing pretty well right now and hopefully we can keep that up tomorrow."
In other men's championship round play, Northern Ontario's Tanner Horgan cruised to a 10-4 win over Ontario's Mac Calwell (2-5). Horgan stole deuces in the first and eighth ends in the victory to improve to 3-4. And Alberta's Karsten Sturmay (6-1) stole a single point in the seventh end, and deuces in the eighth and ninth ends for an 8-3 triumph over B.C.'s Paul Henderson (5-3).
On the women's side, 2014 bronze-medallist Mary Fay of Nova Scotia improved to 5-2 with a 9-6 win over Quebec's Emilia Gagne (4-4). Fay broke the game open with a stolen deuce in the fifth end, and a score of three in the seventh.
Upon completion of the championship round, the top team of each gender advances to its respective final, while the second- and third-place finishers meet in a semifinal to determine the other finalist.