Ovechkin scored the fourth goal of Washington's second-period outburst, leading the Capitals to a 5-1 win over Montreal on Monday night and a 2-1 lead in their Eastern Conference series.
• Brown: Caps unbeaten when scoring shorties
Ovechkin said Sunday that he saw Halak's hand shaking on a replay when the Canadiens goalie took a drink of water after allowing a goal to Fehr on Saturday night.
"Well, I don't know about this game," Ovechkin said. "I didn't see a replay if he was shaking or not but we scored three goals and they had to make some changes."
Ovechkin dropped to his knees at 13:50 to put a one-timer past Carey Price, who relieved Halak after Washington took a 3-0 lead.
Tomas Plekanec spoiled Varlamov's shutout bid with a power-play goal 2:25 into the third.
Matt Bradley restored the Capitals' four-goal lead with 44.1 seconds left in the third.
Game 4 is Wednesday night in Montreal.
Varlamov got his second straight win since relieving Theodore early in Game 2.
"We need our goaltender to be strong and Varly was making big saves that kept us alive and kept our momentum up," said defenseman Mike Green, whose assist on Laich's goal was his first point of the series. "When you have that confidence in your goaltender as a team it's easier to go for goals and make the push. He played outstanding tonight, he was one of the reasons we won."
Theodore, the 2002 Hart Trophy winner as league MVP with the Canadiens, was pulled after allowing goals on Montreal's first two shots Saturday. Varlamov stopped 19 shots the rest of the way for the win in Washington's dramatic 6-5 comeback victory in overtime.
Two nights later, Halak was yanked after he was beaten on three of six shots in the second. The Slovakian goalie stopped 10 shots overall. Price made 21 saves.
Washington's special teams play opened the scoring early in the second as Gordon scored a short-handed goal to put the Canadiens up 1-0.
The Capitals, who have the NHL's top-ranked power play, have not scored a goal with the man advantage in five straight games, including the last two of the regular season.
Gordon, who did not dress for Game 2, backhanded his own rebound past Halak for his first goal 1:06 into the second. Canadiens defenseman Jaroslav Spacek slid backwards into Halak, pushing the Canadiens' goalie into his own net and clearing the way for Gordon's shot.
"That really got us going," said Lach, who added his first goal at 4:42 to make it 2-0. "I think that really calmed us down, but the power play is something we have to address. When we get chances -- four, five, six chances a game -- we've got to come up with one or two goals. That could really sway the series."
Fehr scored his second goal in two games, ending Halak's outing with Montreal in a 3-0 hole before the midway point of the second.
The Bell Centre crowd cheered as Price skated onto the ice.
Booed whenever he touched the puck, Ovechkin increased the lead to 4-0 when he snapped Nicklas Backstrom's feed past Price for his second goal in two games.
"I don't hear it," Ovechkin said. "I just concentrate on where the puck is and where my guy is and just play the hockey game."
Plekanec drew Montreal to within 4-1 early in the third.
Canadiens left wing Michael Cammalleri said "it's all too fresh in my memory" when asked if he could identify a tipping point in the game.
He added, "I think just the feel of the game the second period in general could have been a lot better. One bad period ended up costing us the hockey game."
Canadiens legend Jean Beliveau drew a huge cheer when he was shown on the video scoreboard through the final bars of O Canada prior to the game.
The sellout crowd of 21,273 roared its approval for the end-to-end action through the first half of the opening period, rising to its feet in a standing ovation during a stoppage in play 11:54 in.
Varlamov held the game scoreless through one as he turned aside several good Montreal scoring chances as the Canadiens held a 10-7 edge in shots after the first.
"Varly was very calm back there," Laich said. "He kicked his rebounds to the corner and gave us a chance to come out tied or better. I thought he was fantastic the rest of the night, too."
- Canadiens C Glen Metropolit returned after missing the last six regular season games and first two of the playoffs because of a shoulder injury.
- RW Sergei Kostitsyn was left out of the lineup, and C Ben Maxwell and D Ryan O'Byrne also were not in uniform for Montreal.