The Bruins may not have exactly returned to their winning ways in Ottawa on Thursday, but they grabbed a victory over the Senators – and the officials – anyway.

After the B’s lost a two-goal lead on two Ottawa power-plays – both on questionable calls — Brad Marchand nailed the two points down with an overtime goal to left the B’s to the 3-2 victory.

The B’s didn’t play well in the first or third periods, but they got 35 saves from Jeremy Swayman and came up with just enough offense to escape with a win.

On a 2-on-1 in OT with Charlie Coyle, Marchand kept it for himself and beat Joonas Korpisalo with a far-side wrister. It was his 24th of the year and 396th career goal, pusing him ahead of Ray Bourque for fifth on the B’s all-time goal list.

If the Bruins wanted to atone for their late arrival in Wednesday’s 3-2 loss to Carolina, they kept those intentions hidden well for most of the first period, yet somehow managed to take a 1-0 lead into the first break. Morgan Geekie got a shot on net on the first shift of the game and didn’t get another on Joonas Korpisalo until Jake DeBrusk landed one with 2:22 lift in the period.

The Sens, who held a 9-3 shot advantage in the first, seemed ready to seize control of the game until they got back-to-back plays in the second half of the period. But instead of catapulting them into the lead, it stifled their momentum.

Ottawa couldn’t manage to get a single shot on net in the entire four minutes of PP time and, when the B’s got their first power play when Jacob Bernard-Docker held Geekie with 1:27 left in the period, the B’s wasted no time in cashing in. It took just three seconds for Charlie Coyle to win a faceoff back to Charlie McAvoy and for McAvoy to dish to David Pastrnak in the high slot. Pastrnak, who was held in check by both the tight-checking Winnipeg and Carolina squads, whistled his 31st goal of the season past Korpisalo.

The B’s then took a 2-0 on a Trent Frederic goal in a wild sequence. In the waning sequence of another Ottawa power play, Thomas Chabot came within inches of tying the game he slipped a shot past Jeremy Swayman’s shortside pad, but Swayman swept his left pad behind him to keep the puck from going over the line. Later in the shift, Pavel Zacha found Frederic at the Ottawa blue line and, with Chabot backing in, Frederic snapped his 14th goal over Korpisalo’s blocker at 8:19.

Danton Heinen nearly made it 3-0 on a shorthanded 2-on-1 but Korpisalo made a terrific blocker save and that allowed the Sens to cut the Boston lead in half with 27.5 seconds.

The Sens’ fifth power play off a truly awful tripping call on Frederic on Parker Kelly when Kelly fell over Frederic’s leg during a board battle. It was a stunningly bad call, but the Sens made the most of it on a nice place. Drake Batherson made a pretty backhand pass to Chabot who scored on the backdoor.

After he scored, Chabot belted Parker Wotherspoon and scrum ensued, with each side getting two roughing penalties apiece.

In the third period, the B’s looked gassed on the second half of the back-to-back and played without the puck far too much. It appeared briefly that the Sens tied the game with 6:42 remaining regulation when Josh Norris jammed a puck home. It was quickly taken off the board, however, because it grazed off Mathieu Joseph’s glove immediately before Norris put the puck in the net.

They got the equalizer anyway.

With 4:39 left in the third, Kelly drew another penalty when he went down hard on a forearm shove by Wotherspoon, deemed a crosscheck by the officials. And again, the Sens cashed in with 3:18 left in regulation when Vladimir Tarasenko sniped a tough angle shortside wrister to tie the game.