Stomachs churn. Muscles ache. What-ifs spin through the brain.

“It’s never easy to sleep after an overtime loss,” Derek Stepan said Saturday.

For the Rangers, Friday night’s 4-3 overtime loss to the Canadiens in Game 2 of their first-round playoff series was excruciating because the Blueshirts were 17.3 seconds away from taking a 2-0 series lead. But Montreal scored to tie it and won the game late in overtime.

Trailing by a goal in the third, the desperate Canadiens made a big push in the last 10 minutes of the period while the Rangers — in their own words — sat back and tried to protect the lead. That fact kept Stepan and the Rangers tossing and turning in their Montreal hotel.

Imagine the nightmarish mental replay: With Carey Price pulled for an extra skater, Tomas Plekanec’s sliding shot went past a stickless, kneeling Nick Holden and Henrik Lundqvist into the far corner of the net with 17.3 seconds to play to tie it at 3 and force overtime.

Lundqvist was stellar, making a career-high 54 saves, but after the shock of allowing the tying goal and having emptied the tank defending, the Rangers had little left to generate enough chances against Price in overtime, managing only eight shots on goal to Montreal’s 13.

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Canadiens defenseman Shea Weber blasted a shot in overtime off a rush that beat Lundqvist, but it hit the post.

Finally, in another in-the-paint battle, the lasting image was of Alexander Radulov jamming a rebound under Lund qvist with 1:26 left in overtime.

The overtime goal was set up by one of the Canadiens’ top scorers, forward Max Pacioretty, who stole the puck from Rick Nash at center ice and started the winning play. Nash had scored midway through the second period to tie the score at 2.

“We were just trying to find a way to hang on,” Stepan said. “In OT, we were playing a little too safe. After they score a goal, you have to be able to get back on your toes . . . and make adjustments.”

The strategy wasn’t totally wrong, Stepan insisted. “You watch all the playoff games, teams get up by a goal, they play high-percentage; we were 17 seconds away,” he said. “We needed to get on the forecheck. That would be my adjustment.”

The Rangers, who won Game 1 on Wednesday, 2-0, now need a quick bounce-back at home. Game 3 is Sunday night at Madison Square Garden, with Game 4 at MSG on Tuesday night.

Although the Rangers were 21-16-4 at home during the season, players said there won’t be a carry-over.

“In the regular season, we had our struggles,” Nash said, “but this is a new season, and everything that has happened before has been erased.”

Scoring three goals against Price, who is as elite a goaltender as Lundqvist, provides some confidence, and Nash said: “I still think we can get more traffic in front of him. There’s always lots of momentum swings. After that last goal, it’s hard to say they don’t have some [momentum], but we split the series there. There’s got to be some momentum in that, too.”

The Rangers said they have several objectives at home: to ratchet up their speed, box out effectively to prevent crease-front goals and feed off the energy of the home crowd, as the Canadiens did at Bell Centre.

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“When you get into a playoff game, there needs to be some physicality,” Stepan said, “and we want to use our speed. We’ve got to find a balance; if we’re sharp through the neutral zone, we’ll get our looks.”

Even with very little sleep, along with the what-ifs, Saturday brought some perspective. “We’re pretty familiar with each other and the matchups out there now,” said Ryan McDonagh, who played a team-high 33:18 Friday night. “We’re just focusing on trying to have a good start [at home] and have some pride there.”

Blue notes

There have been no power-play goals in the first two games: the Rangers and Canadiens both are 7-for-7 on the penalty kill . . . The Rangers have a 6-3 record in the last nine series in which they split the first two games . . . The combined hits in the first two games were 227 (Rangers 119, Canadiens 108). The 74 hits by the Blueshirts on Friday night (Tanner Glass had a game-high 10) were the most the Rangers have had in a playoff game since the NHL began to track hits in 1997-98.