CALGARY, Alberta -- Sean Monahan was the one who scored in overtime Tuesday, but he gave his linemate Johnny Gaudreau most of the credit.

The Calgary Flames center scored at 2:26 of the extra session to lead his team to a 4-3 victory over the Buffalo Sabres at the Scotiabank Saddledome.

Monahan took a nice saucer pass from his left winger and snapped a shot past Buffalo goaltender Robin Lehner to give the Flames (1-2-1) their first win of the season.

"I just tried to get open," said Monahan, who has two goals in four games. "Johnny had the puck. When he has the puck you try to find a soft spot. He threw a sauce on my stick. It was a great play there by Johnny."

Right winger Micheal Frolik, left winger Micheal Ferland and rookie left winger Matthew Tkachuk also scored for the Flames (1-2-1), while goaltender Chad Johnson made 18 saves against his old team.

"That was huge," Monahan said of Johnson, who signed as a free agent with the Flames in the off season after compiling a 22-16-1 record last year with the Sabres to go with a 2.36 goals-against average and a .920 save percentage. "It's his old team there. He's confident in his crease. He's moving the puck well and made some huge saves and kept us in the game."

Zemgus Girgensons, Ryan O'Reilly and Marcus Foligno scored for the Sabres (1-1-1), while Lehner stopped 30 shots.

"We've got to play better," Lehner said. "We got away from our game plan a little bit. To be fair, Calgary kept going. I think we gave them a little bit too much."

Despite scoring his third goal of the season, O'Reilly wasn't happy that the Sabres weren't able to hold onto leads of 1-0, 2-1 and 3-2.

"I don't think there's many positives to take at all," O'Reilly said. "Our compete level, our execution was just embarrassing. That's not the way we want to be. We want to be a consistent team. We have to be a lot better."

Ferland backhanded a shot to the top corner past Lehner a 1:10 of the third period before Foligno replied with a goal for the Sabres at 3:49.

The barrage of goals continued as Tkachuk scored his first NHL goal 1:03 later. Tkachuk took a pass from center Matt Stajan and snapped a shot to the short side past Lehner to tie the score at 3-3.

"Obviously unbelievable," said Tkachuk of his milestone moment. "You dream about scoring in the NHL for a long time. Now that I've got the first one out of the way, hopefully we can just keep rolling as a team and keep putting the puck in the back of the net like we did tonight."

The Sabres went up 2-1 with a power-play goal at 11:41 of the second period. Johnson made the initial save to stop a slap shot off the stick of O'Reilly, but the puck bounced off Flames defenseman Dougie Hamilton and into the net.

During an early power-play opportunity in the first period, Flames right winger Alex Chiasson tipped a shot taken by left winger Ferland on net that Lehner was able to turn aside. Lehner then stopped Ferland's rebound attempt to keep the game scoreless.

Girgensons swatted a nice feed from center Tyler Ennis past Johnson at 7:25 of the first to put the Sabres up 1-0.

The Flames pulled even at 16:12 when Frolik tapped a loose puck in the crease past Lehner, who blocked a point shot by defenseman Brett Kulak before also turning aside a shot by center Mikael Backlund. For Kulak, it was his first NHL point in his 11th game.

NOTES: Sabres C Derek Grant spent last year in the Flames' organization. Although he only had one assist in 15 games with the Flames, Grant led the AHL's Stockton Heat with 45 points (27 goals, 18 assists) in 36 games. ... After being called up from the AHL's Rochester Americans on Saturday, Sabres RW Nicholas Baptiste made his NHL debut on Tuesday in Calgary. He was a plus-1 in 8:50 of ice time covering 14 shifts. ... Buffalo's healthy scratches were D Casey Nelson and RW Hudson Fasching, while LW Evander Kane is out week-to-week with cracked ribs. ... The Flames went with the same lineup that they did in a 2-1 shootout loss to the Canucks in Vancouver on Saturday, meaning that D Dennis Wideman, D Nicklas Grossmann and C Freddie Hamilton were healthy scratches. ... The Flames announced Monday that they signed G Tom McCollum to a two-year, two-way contract and then assigned him to the AHL's Stockton Heat.