The team stayed quiet about his return from a lingering neck injury until the puck was dropped Tuesday night and the veteran forward made quite an impact once he got on the ice.
The goal and assist were the first for Gagne since joining the Lightning from the Philadelphia Flyers in a trade last summer. He missed the previous 18 games with persistent pain in his neck that caused some blurred vision.
"We kind of kept [the return] secret this morning just in case," Gagne said. "I was nervous. I didn't sleep a lot last night -- even this afternoon I was looking for at least a good two hours for a nap, but I could not sleep. It's hard when you don't play for a month and you're coming back in Toronto. You know it's going to be a tough game.
"I'm glad this one's over and I'm glad we won the game," he said.
They couldn't have done it without him.
First-year Lightning coach Guy Boucher has been widely praised for his attention to detail. He cracked a big grin when asked about keeping Gagne's return to the lineup under wraps.
"Anything we can do to make sure that the players are able to focus on what they've got to do," Boucher said. "Especially in a situation like this where it's big for him to come back and wonder how it's going to go. I think you keep it down to the smallest expression coming into today [so he can] just think of his game. I think it was really important.
"[It's] pressure off him ... and I think it worked out pretty good," he said.
The Lightning have received a lot of attention during the first two months of the season, but it was seldom directed toward Gagne, a former 40-goal scorer and two-time Canadian Olympian who has battled a number of injuries.
Even though the team was able to get by with big contributions from St. Louis and NHL goals leader Steven Stamkos, Gagne's presence was missed.
"It's been really hard," St. Louis said. "He's a battler, he's a guy that wants to be out there and help his team win. It's not only been tough for him, it's been tough for us to not have him. You know what he can bring.
"We're happy to have him back," he said.
The overtime winner came on a two-on-one rush with Brett Clark. Gagne elected to shoot rather than pass and he beat goalie Jonas Gustavsson high. That finished off a comeback after St. Louis tied the game with a pair of third-period goals.
Ryan Malone also scored for Tampa Bay.
The Maple Leafs appeared to go ahead 2-0 before the intermission, but Luke Schenn's goal was quickly waved off because Clarke MacArthur was deemed to have interfered with goalie Dan Ellis. Replays showed MacArthur getting nudged into the crease by Tampa Bay defenseman Victor Hedman.
"That should have been a goal," Toronto coach Ron Wilson said. "I think when the referee reviews it himself and he sees it, [he'll agree]. ... He told me [MacArthur] was in the crease the whole time and he wasn't. He was pushed into the crease by the defenseman as the puck was entering the net.
"I have the advantage of replay so I can be critical of it, but it looked like a good goal from the bench and then when we watched the replay, I'd say it was a good goal. You can't argue that," he said.
Toronto has dropped 15 of 19 since opening the season with four straight victories.
Tampa Bay tied it at 1 after a nice play by Gagne, who was in the lineup for the first time since Oct. 21. He stopped the puck behind the goal and got it quickly to Malone, who beat Gustavsson with a wraparound at 5:18 of the second period.
Kulemin put the Leafs ahead by two goals with a hard shot from the top of the circle on a power play at 11:51 before adding an insurance marker just more than seven minutes into third, knocking in a loose puck after it had taken a funny bounce off the boards and fooled Ellis.
St. Louis took over from there, beating Gustavsson from in close just more than a minute later before sending the game to overtime by blasting a shot past the Toronto goalie.
The decision to shift Nazem Kadri to center on Toronto's top line with Phil Kessel and MacArthur didn't yield any results. The unit appeared disjointed at times and Kadri struggled with the move back to center -- winning just three of 16 faceoffs through 40 minutes -- before being replaced by Tyler Bozak late in the game.
The Maple Leafs did manage to contain Stamkos. He was held without a goal, making it the first time all season he's gone three games without scoring.
Kulemin took three minor penalties. He was called for two in the first 22 games. ... Toronto's Joey Crabb played the 30th game of his NHL career after being recalled from the AHL Marlies. ... John Mitchell and Brett Lebda were healthy scratches for the Maple Leafs. ... The Lightning dressed seven defensemen. ... Stamkos has six goals and 14 points in 10 career games against Toronto. ... It was the sixth straight start in goal for Gustavsson. ... Announced attendance was 19,063.