The Bruins defenseman played a game-high 26 minutes and saved his best for the final one, using his skill and speed to create multiple chances capped by Zacha’s fourth goal of the season.
“Charlie made a hell of a play,” said Bruins coach Marco Sturm. “For big win.”
Zacha said getting the puck on McAvoy’s stick was a priority in overtime, where the extra ice gives players with his ability to accelerate an advantage.
“He’s a great skater and he beat his guy and made it a two-on-one and then he made a great play,” said Zacha. “So, I think that’s something in overtime that he used his skill and took over.”
The Bruins’ sixth victory in the last seven games pushed their record to 9-7 and avenged the worst loss of the season: a 7-2 drubbing in Ottawa a week ago.
“I think that was a big motivation for us,” said Zacha. “We had a bad game there and lost pretty badly, so I think before the game we were motivated to give it back and I’m happy that we won.”
The Bruins outplayed, outhit, and outshot the Senators through 20 minutes but still were looking at a 1-0 deficit as they headed to the locker room.
Unlike the first matchup when the Bruins had trouble getting out of their own way, they controlled the pace for most of the period.
It was the Senators, however, who struck first — and on their first shot of the night. It was one of only two they landed on goal in first.
Jonathan Aspirot got caught flat-footed in the neutral zone, leading to an Ottawa two-on-one.
Shane Pinto took control and feathered a pass to Michael Amadio, who settled the puck and snapped it past Joonas Korpisalo (20 saves) just over five minutes in.
Joonas Korpisalo (No. 70) denies Senators center Shane Pinto (12) from point-blank range in Thursday’s 3-2 overtime victory at TD Garden.Matthew J. Lee/Globe Staff
From there, the Senators didn’t threaten Korpisalo’s cage again until there was less than a minute to go in the period.
The Bruins meanwhile had the ice tilted in their favor for lengthy stretches with the second line of Casey Mittelstadt, Zacha, and Viktor Arvidsson creating myriad chances but no goals.
Morgan Geekie had the Bruins’ best chance after being sent in a partial breakaway by David Pastrnak.
Geekie avoided a check by Nick Jensen and sent a wrister that whistled by Ullmark (22 saves), off the crossbar, and finally off glass.
The Bruins played the final 40 minutes without fourth-line winger Johnny Beecher, who suffered an upper-body injury after a couple of hard thuds into the boards.
The Bruins continued to outwork the Senators in the second and were rewarded with a 2-1 lead after 40 minutes.
Geekie cashed in his team-leading 10th goal of the season for the equalizer and, quite frankly, deserved an assist on the tally as well.
Geekie hounded Nick Jensen on the forecheck, forcing a fumble that he pounced on and sent through the slot. The puck ricocheted to Andrew Peeke, who rocketed one off Ullmark and the post, the puck falling dead in the blue paint, where Geekie whacked it home.
It was Geekie’s eighth goal in the last nine games.
Tempers flared after the equalizer with Mark Kastelic and Kurtis MacDermid going for matching roughing minors.
With the crowd still buzzing after the skirmish, Nikita Zadorov crunched Tim Stutzle behind Korpisalo’s net moments before Kleven put a big hit on Peeke that bent the Bruins defenseman backward at the Boston bench.
Peeke briefly went to the room for repairs but only missed a few shifts.
Sean Kuraly gave the Bruins the lead, capping a nice individual effort by Tanner Jeannot.
After scoring his second goal of the season, giving the Bruins a 2-1 lead in the second period, Sean Kuraly said he knew precisely how he was going to celebrate it: with a leap of faith. “It wasn’t rehearsed, but the second it went in, I knew what I had to do,” he said.Matthew J. Lee/Globe Staff
The Senators gave Jeannot space as he raced up the left wing. He pulled up at the dot as defenders converged and hit a charging Kuraly, who snapped one past Ullmark before leaping into the glass to celebrate.
“It was overdue,” Kuraly said of the jump. “So, actually it wasn’t rehearsed, but the second it went in, I knew what I had to do.
Ageless Claude Giroux tied it for the Senators midway through the third, but the Bruins showed resiliency and maturity. Whereas earlier it could have led to collapse, instead it led to a comeback.
“Well, I think what we learned during that [six-game] losing streak is just hang around for a second and don’t shoot yourself in the foot after,” said Kuraly. “Let’s go out there, let’s get a couple shifts. Number one is just get out of our end and then eventually, they’ll make a mistake, too.”
Jim McBride can be reached at james.mcbride@globe.com. Follow him @globejimmcbride.