The first drops of bad blood were spilled about halfway through the second period.
Then, at the final horn of a 4-3 home victory, most of the 12 Montreal Canadiens and Ottawa Senators who were then on the ice at the Bell Centre gathered in a corner to shed helmets, tug jerseys, wash a few faces and exchange bon mots – even goalie Habs Carey Price tossed aside his trapper and waded in.
Calm was eventually restored. No one involved expects it to last.
Recriminations swiftly followed post-game, the rivalry between the geographically-proximate clubs is heightening.
The Senators were patently upset at Montreal defenceman P.K. Subban for a two-handed whack on Ottawa winger Mark Stone's hands in front of the Habs net during a second-period Sens power-play (the Habs had taken a 2-1 lead on goals 15 seconds apart a few moments earlier).
Subban was assessed a major penalty on the play, which by rule must be accompanied by a game misconduct.
"Lumberjack slash," is how Ottawa forward Clarke MacArthur described it.
Stone and Sens coach Dave Cameron called on the league to consider a suspension Subban, one of the league's very best defencemen.
The Senators coach even went so far as to say that if Subban isn't suspended perhaps one of his players will trade five minutes and a game for a chance at slashing one of Montreal's better players.
Stone, who left for the dressing room on a couple of occasions but finished the game on the ice, called it a "pretty big hack, it looked like he wanted to hurt me."
"He'd been doing it a couple of times, he tried targeting me a couple of times in the first period off faceoffs, I think he knew what he was doing," he said.
When he was asked point-blank whether Subban should face supplemental discipline, he said "I do, yeah, of course. I thought there was some intent there."
Subban wasn't around to recount his version of events, television replays showed him in the tunnel reacting angrily to Stone's return to the game, team officials said afterward he had left the building.
Montreal coach Michel Therrien said the slash was an obvious penalty ("it was a pretty good whack of the Sher-Wood, as we used to call it") but that it fell short of the standard for a major.
Asked whether he felt his star defenceman would be suspended he shrugged and said "I didn't think it was worth five minutes."
There were multiple reports late Wednesday night that Subban likely won't face any additional punishment.
The incident is not without parallels to game one of the last series in which these two teams faced off – although Stone isn't nearly as badly injured as Montreal's Lars Eller was in the second period of that game (and Eric Gryba was hit with a two-game ban for the hit that sent him to hospital).
Former Senators coach Paul MacLean defended Gryba and memorably laid the blame at the feet of "player 61" – former Habs defenceman Raphael Diaz – for sending Eller a dangerous pass.
Montreal's Brandon Prust then dismissed MacLean as a "bug-eyed, fat walrus".
Stone, of course, wears 61 for the Senators.
He may rightly feel he was singled out for rough treatment in this game; there was lots of that going around on both teams.
Montreal's Brendan Gallagher was fed a steady diet of abuse by Sens defencemen Marc Methot and Mark Borowiecki, who hit, cross-checked, slashed, body-slammed and otherwise beat on him whenever the opportunity arose.
All's fair in love, war and the NHL Stanley Cup playoffs.
"You couldn't have drawn it up better . . . it was a close game, it was chippy, that's what you're looking for in a playoff game," said Montreal blue-liner Tom Gilbert, one of several players to be hit with a misconduct at the 20:00 mark of the third.
Added Eller: "I play my best when I'm a little bit pissed off . . . and it's definitely easier to get pumped up for teams we have a history with."
As damaging as the Subban slash could be to Ottawa's hopes – Stone is a key cog and has scored a season's worth of clutch goals in the past three months – their main cause for regret will likely be the 15-second passage of play that came a few minutes before it.
The Sens had taken the lead on a fortuitous bounce – as Subban and Mika Zibanejad jousted while chasing a clear-in, Montreal's Andrei Markov chipped a loose puck through Price's legs and into the net ("just a bit of misfortune," Therrien said) – but the Habs had tallied twice in the space of 15 seconds to take the lead.
First, Torrey Mitchell of Greenfield Park, Que., scooped up a puck behind the net and scored a wraparound goal on Andrew Hammond.
It wasn't the Hamburglar's finest hour, and moments later he wasn't able to stop a Tomas Plekanec snipe from squeezing through his legs – it didn't help that Plekanec roared down the ice on a two-on-one after the puck skipped past Ottawa defenceman Erik Karlsson at the offensive blue line.
When Eller was penalized for a skirmish with Zibanejad and Subban followed him into the box, Kyle Turris knotted the game at 2-2.
But then Montreal took a surprise lead while short-handed, David Legwand's pass to Cody Ceci at the point ended up getting stuck in the defenceman's feet, Eller and Brian Flynn set up the ice, the latter's diving pass to the former ending up in the top corner on Hammond's blocker side.
Ottawa nevertheless tied the game through Zibanejad at the tail end of Subban's penalty.
Flynn, however, scored the decisive goal on another iffy play from Hammond, who couldn't stretch a toe to stop his low shot when the Montreal fourth-liner pounced on a defensive breakdown and took the puck to the net.
There will be much ink spilled about Subban, Hammond and Price (who allowed three goals for the third consecutive game but played brilliantly once Montreal took the lead).
Few would have guessed that a pair of deadline-day pickups from sad-sack Buffalo – Flynn and Mitchell – would have such a key impact on the game.
"If you'd asked us three months ago if this is where we'd be standing I think we'd take it," grinned Mitchell, plainly exultant at having played his first post-season game (and potted his first career playoff goal) in the jersey he grew up worshipping. "I was getting a lot of text messages from a lot of buddies back in the Park."
Flynn had three points on the night – an NHL first.
"It's obviously one of highlights (of my career) if not the highlight . . . I was really looking forward to tonight," said the Massachusetts native.
The play of Flynn and Mitchell, as well as that of mid-season acquisitions Jeff Petry and Devante Smith-Pelly, will only grow general-manager Marc Bergevin's legend.
Petry played brilliantly as the Habs filled the void left by Subban's early exit, Smith-Pelly set a physical tone early on and was unlucky not to score a third-period insurance goal – his shot was deflected onto the post by Hammond.
The Hamburglar has been brilliant since making his NHL debut earlier this season and backstopping his team's improbable run to the playoffs, but questions will necessarily arise after a second period where he allowed four goals on 14 shots.
The Senators might hope the Subban storyline is kept alive for a few more days.