With the Winter Classic this Friday, into TD Garden Tuesday night skated the Ottawa Senators, who took out Boston Sunday night, 3-1, for the Bruins third consecutive regulation loss. Boston had not lost four straight in regulation since March 2012.

Losing David Krejci in Sunday’s loss and Torey Krug in Saturday’s meltdown to Buffalo added up to some tough sledding for Boston into Friday’s mega showdown at Gillette Stadium.

“When you lose a guy like Krejci [and Chris Kelly and Joonas Kemppainen],” Claude Julien said Tuesday morning, “you know you got thinner and thinner, and you’re probably at your thinnest right now.”

Krug returned Tuesday night while the team recalled Seth Griffith to fill some of the Krejci void.

Here’s what we learned after the Bruins bounced back from three losses with a 7-3 win over Ottawa that ended the way many Bruins’ game did in the years of Sanderson, O’Reilly, Jonathan and the Big Bad Bruins of yesteryear.

The power play was sizzling

At 1-1 late in the first period, Patrice Bergeron scored on the man-advantage at 16:25 to give his team the lead. It was his 13th of the season with Torey Krug and Ryan Spooner assisting. At 1:21 of the second, Boston upped the lead to 3-1 when Matt Beleskey scored with Brett Connolly and Brad Marchand assisting. On their fifth PP, Bergeron tipped a Torey Krug blast from the point with Griffith assisting. The goals were Boston’s 27th, 28th and 29th of the season with the man advantage. Hayes’ heroics — see below — gave Boston its fourth power play goal and the team’s 30th of the season.

“We had a chance to win [Sunday’s game],” Julien said Tuesday morning, ”so if we find some ways to score some goals I think that would be the only adjustment I would talk about.”

Meltdown averted

For the second game in a row at home, Boston took a 3-1 lead, only to have it reduced to one goal when Mike Zibanejad scored at 17:51 of the second period. Saturday, the Sabres put a 5-goal warhead on Boston’s 3-1 lead to win going away, 6-3.

After Bergeron put Boston up, 4-2, it was nail-biting mode when Mike Hoffman cued one off Dennis Seidenberg’s skate past Rask at 4:22 to make it a 4-3 game.

But Max Talbot and Jimmy Hayes put the cherry on the Sunday at 15:49 when they put on a 2-on-1 clinic with Hayes beating Craig Anderson. Beleskey followed with his second of the game at 16:40; Spooner and Loui Eriksson assisting.

“I like the fact that our group is really coming together,” Julien said. “Even though we lost the last three games. We blew a lead against Buffalo you know so we had to learn that tonight coming in with a one-goal lead in the third that we had to be better.”

Hayes tallies first NHL hat trick.

With two-tenths of a second on the clock, Hayes completed his first NHL hat trick in the 7-3 final. Frank Vatrano and Dennis Seidenberg assisted.

“We talked about him scoring some goals with his size and his strength,” Julien said about Hayes’ output, “tight around the net and that’s what he did tonight. So hopefully he sees that, builds on that and continues to produce for us.”

“It was good to see that,” Tuukka Rask added. “He hasn’t had a lot of success scoring goals lately.”

“I liked the way that they were thinking in a 6-3,” Julien said about the team support for Hayes to get his third goal, “and that they are trying to help their teammate out.”

A milestone for Krug

Torey Krug’s assist on Bergeron’s second power-play goal was his 100th NHL career point. He did it in 195 games, an impressive half-a-point per game average — a stat most current forwards would die for.

“We weren’t expecting him to be in the lineup tonight,” Julien said about his prized blueliner, “and then we got some news at some point that it was a good possibility.”

Chara gentle(man) with Borowiecki

At 13:14 of the second period, 26-year-old Ottawa defenseman Mark Borowiecki and Zdeno Chara got into a scuffle next to Tuukka Rask. Both dropped the gloves, and the 38-year-old dropped Borowiecki without a punch thrown. Boston’s captain had Borowiecki in a vulnerable position, but took the gentleman’s route, settling for matching minors for roughing –and saving Borowiecki a few stitches to the chin.

Game ends with a throwback

“Whether some people think it’s team building,” Julien said about the melee the last 60 seconds. “It’s great for your group, to a certain extent it is but you don’t want to see that every game. It happened tonight and usually those things can happen on those home and away games with the same team.”

With a minute to go, Landon Ferraro and Max McCormick got into it with 5-minute majors each. That was just a prelim. Thirty-four seconds later, all hell broke out when no less than three bouts took center stage, the two feature bouts between Zac Rinaldo and Dave Dziurznski, and McQuaid and Chris Neal. A total of 82 minutes were called on both teams in those final 60 seconds.

Friday afternoon, the NHL takes center stage at Gillette Stadium as the Bruins look for their 3000th win in franchise history.

“Hopefully we can enjoy a day tomorrow over there with family, relax and then get back to work the following day preparing for that big game,” Julien said.

Tuesday night’s power surge with the Bruins’ highest goal total of the season will help with that.

Happy New Year, folks.