Bruins defenseman Charlie McAvoy lands on Panthers center Anton Lundell after a hit during the third period of Boston’s 4-2 win in Game 3 of their first-round playoff series on Friday in Sunrise, Florida. Lynne Sladky/Associated Press

Five seconds into the game, Charlie McAvoy seized an opportunity to set a tone for the Bruins and send a message to the Florida Panthers before the ice was even scratched.

With Patrice Bergeron and David Krejci out, McAvoy is one of the players the Bruins count on to fill their leadership void despite being just 25 years old. So when Eetu Luostarinen came down the left wing boards in the neutral zone, McAvoy led by example, lowering his shoulder and sending the forward sprawling.

It was pretty indicative of how the game was going to go. In the first two games, Florida gained an edge by being more physical. The Bruins came out intent on reversing that in Game 3, and McAvoy led the way in a 4-2 win.

“I thought what set the tone was Charlie McAvoy laying a big hit in the first shift,” said Taylor Hall, who scored not long after McAvoy’s hit. “That was a telltale sign of how hard we were going to play.”

It was one of several big hits McAvoy delivered. He legally flattened Anton Lundell in the third period, causing Aleksander Barkov to wrestle
McAvoy to the ground from behind. Unlike in Game 2, it was Florida that lost its composure late.

It wasn’t just being more physical. The lack of Bergeron and Krejci combined with Coach Jim Montgomery’s roster shakeup caused the Bruins to simplify their game. With unfamiliar lines, many of the players didn’t have the familiar chemistry to get too fancy. For one night at least, it was a temporary blessing. They were physical, played mostly straight ahead and regained their confidence while stripping Florida of the momentum it gained in Game 2.

“This was a pivotal game for us,” Hall said. “We know how good they play at home and how tough of a time they gave us in the first two games.”

Nick Foligno agreed.

“If our team plays with that mindset, that mentality, that attitude, I think it’s going to bode well for us further down in the series,” he said.

AFTER WINNING WITHOUT their top two centers in Game 3, the Bruins might have to do it again in Game 4.

Krejci was a late scratch for Game 3 because of an upper-body injury, joining Bergeron, who didn’t make the trip, among the Bruins inactives.

Boston scored the first four goals and held on for a 4-2 win to take a 2-1 series lead.

While the move came as a surprise to a lot of people, Montgomery said the Bruins were prepared for it Friday and could deal with it again on Sunday.

“We knew there was a good chance he wasn’t going to play tonight,” Montgomery said after the game. He said Krejci’s chances of playing in Game 4 were “50-50.”

Krejci missed the last four games of the regular season because of a lower-body injury, but returned for the first two games of this series.

Nick Foligno, who was initially pulled from the lineup as part of Montgomery’s roster shakeup, replaced Krejci and scored Boston’s fourth goal.

The absence of the two centers and Montgomery’s moves created some unfamiliar lines.

Charlie Coyle centered Brad Marchand and Jake DeBrusk. Pavel Zacha was between Tyler Bertuzzi and David Pastrnak. Trent Frederic centered Taylor Hall and Nick Foligno, and Tomas Nosek was in the middle of Jakub Lauko and Garnet Hathaway.