Miller made a pad save to deny Canadiens captain Saku Koivu's backhand attempt, and Vanek stunned the sellout crowd when he wound up and fired a slap shot over Huet's right arm into the top left corner.
"With Thomas, there's nothing that surprises me," Ruff said. "I thought he might have faked it, but I've seen other guys in the league do it, and I think the odd time it catches the goalie a little bit off guard. It was a terrific shot, and in the right spot."
Huet, who made 31 saves in regulation and overtime, acknowledged that Vanek's choice was surprising even though he noted that other players have recently scored off slap shots in the same situation.
"He's a very skilled guy and I wasn't expecting that," Huet said. "I think he wanted me to go down, but he let it go."
Miller, who also turned aside 31 shots, stopped Sergei Samsonov to give Buffalo its fourth win in six games.
"It's important to get the first shot, and if you don't get it, you just move forward," said Miller, who never watches his teammates' shootout attempts.
"From a structure standpoint, our game was so much better than it was the other night," Ruff said.
Montreal defenseman Sheldon Souray scored his team-leading 11th goal 2:52 into the third to tie it at 2. Souray, who assisted on Montreal's other goal, left the game with an apparent right arm injury before the midway mark of the period and didn't return.
Canadiens coach Guy Carbonneau was unsure of the extent of Souray's undisclosed upper body injury and said he would be re-evaluated Sunday.
"Hopefully, (Sunday) will just be a treatment day for him and he'll come back on Tuesday, but if not, somebody else will replace him," Carbonneau said.
Michael Ryder scored his eighth goal on a power play midway through the second for the Canadiens, who got both goals in regulation with the man advantage, tying the game each time.
Montreal went 2-for-4 with the man advantage and successfully killed each of Buffalo's five power plays. The Sabres have scored just three times in 41 chances.
"They won the special-teams battle. You've got to give them a lot of credit for that," Ruff said. "Their penalty killing has been very good, their power play, with Souray shooting the puck, has been very dangerous, so I like the way that team's playing. They're a tough team to play against and you can see why they've won as many games as they have. They're on top of a lot of parts of their game."
Miller denied a Canadiens' short-handed chance early in the second when he stopped Koivu, who chose to shoot on a 2-on-1 with Steve Begin.
Novotny opened the scoring with his sixth goal 6:12 into the second.
Ryder tied it at 9:11 when he jumped on a loose puck and beat Miller from after Souray's slap shot from the point struck Koivu in front of the net.
Roy restored the Sabres' one-goal lead with his fifth of the season at 17:45.
- The Sabres announced that D Teppo Numminen has a broken right toe. The 18-year veteran was injured Thursday during a loss in Florida. D Andrej Sekera was called up from Rochester of the AHL to replace Numminen in the lineup. He made his NHL debut.
- The Canadiens have sold out 74 consecutive regular-season games.
- D Janne Niinimaa and LW Garth Murray didn't dress for Montreal.