Now the Lightning need to find ways to keep on winning without their offensive motor and one of the NHL's biggest stars.
"We don't have much time to think about it," defenceman Eric Brewer said Tuesday ahead of the Bolts' game against the Montreal Canadiens. "We're not going to replace that loss, but we can try to deal with it and play well and carry on."
Stamkos underwent surgery Tuesday in Boston to repair a broken shin bone. The 23-year-old will be out indefinitely.
"I can't give you a timeframe on whether he's going to be eight, 12, 16 weeks or months, Lightning general manager Steve Yzerman said in Toronto. "I can't give you a timeframe on that. All I can say is he's out indefinitely for now. I think after speaking with the doctors, after today probably we'll have a better idea of the timeframe."
Even his participation for Canada at the 2014 Winter Olympics in February is in some doubt.
"He had his procedure done this morning, and I'm waiting to hear back from one of the trainers who stayed at the hospital with him," Yzerman said. "But the procedure was done, the trainer will speak to the doctor, the surgeon, at the end of the day to kind of explain exactly what was done and the near-term, I guess, procedures for initial rehab.
"He will start rehabbing immediately, but by all accounts everything went well today. There was no unexpected issues."
Stamkos was backchecking hard against Boston defenceman Dougie Hamilton in the second period of a Monday afternoon matinee when he lost his footing. His left foot hit and dislodged the net and his right leg swung round and struck the post.
He tried to get up twice, but could only lay down and pound the ice with a fist in pain before he was taken off on a stretcher.
"He's a tough guy," added Brewer. "If he could have peeled himself off the ice he would have.
"When he's not able to get off the ice, you know something's really not right."
It is the first major injury of Stamkos' career. Yzerman said he talked with Stamkos on Monday night.
"In the brief period that I did speak with him, he was, I guess — not surprising if you knew him — particularly upbeat," Yzerman said. "He said, 'I'll come back stronger than ever.' All things considered he was in good spirits."
Stamkos missed three games as a healthy scratch in his rookie season in 2008-09 and hasn't missed a game since.
"I don't remember him even missing a practice," said Brewer. "He's clearly a huge part of our team and a guy people come to see in every building we go to.
"We hope that he'll have a speedy recovery."
Tampa Bay went into Boston on a four-game winning streak. The game was scoreless until Stamkos got hurt, and then the Bruins went on to win 3-0.
The Lightning hope that wasn't an omen.
They were first in the Eastern Conference with 24 points (12-5-0) through 17 games thanks to a combination of a conference-best 54 goals scored and much-improved defensive play and goaltending.
Now they'll have to find a way to win without Stamkos, who was tied for the NHL lead in goals (14) with Alex Steen of St. Louis and in points (23) with Pittsburgh's Sidney Crosby.
The two-time Rocket Richard Trophy winner as the league's top goal-scorer has the ability to make goals happen on his own — a weapon that will now be missing.
"He's pretty much good for a goal a game," said forward Ryan Malone. "For us, it's a group effort.
"It's our job as a team to stick together and keep moving forward."
The player most affected will be Stamkos' long-time linemate, 38-year-old right-winger Martin St. Louis.
"Stammer's goals are going to be missed, but other guys are going to have to score more," said St. Louis. "It starts with me.
"I have to be better. Hopefully I'll be able to lead the way here with what we've got coming in the next few months. It's not going to be one guy. It's going to be everybody. But this is the time when you want to play well for a guy who has given everything for this organization. It's time to go to work."
Cooper called a team meeting ahead on an optional skate at the Bell Centre on Tuesday morning. He now has to convince his players they can keep winning if they trust in their defence-first system, which emphasizes team play over the individual.
Even Stamkos was buying in. Cooper noted Stamkos was backchecking when the injury occurred.
He also pointed out that they were 2-1-0 before Stamkos scored his first goal of the season in their fourth game and that, while he played 20 minutes per games, other players have done well in the other 40 minutes.
And he appealed to the players' pride.
"I'm not sure anyone was picking the Tampa Bay Lightning to be anything but a team that other teams would pass going into the playoffs," he said. "We were just getting to the point where people were thinking that these guys might be for real.
"But in the second period (on Monday), those people who though we were for real were right back to saying 'these guys are done.' This is what everyone in this room says: Let's prove to everybody we're not a fluke. We're at the top of the standings for a reason and we're going to stay there."
It's not that Stamkos won't be missed, however. Cooper said he was a leading candidate for the Hart Trophy as the league's most valuable player before the injury.
"It is too bad because he was a pleasure to watch," the coach said. "I can't say when he's coming back, but he'll be back.
"This is just a short term hiccup and it's a challenge for us. But if anyone's going to get back fast it's Steven. He's a tough guy to keep off the ice in any situation. This is a bump in the road for him."
The Lightning had no injuries this season until they got to Boston. In the same game, defencemen Sami Salo and Keith Aulie were also injured, although not as badly as Stamkos. Speedy forward T.J. Brown and rearguard Dmitry Korobov were called up from AHL Syracuse.
The schedule is about to get busy. The Bolts play Thursday at home against Anaheim, then have four games on the west coast.
With files from Canadian Press reporter Stephen Whyno.