Marchand scored his eighth goal in eight games to help Boston erase a two-goal deficit, and Ryan Spooner scored in regulation and the shootout to lead the Bruins to a 3-2 victory Thursday night.
With his team down 2-1 and killing a penalty, Marchand picked up a Sabres turnover in his own end and started an 11-second rush that saw him drag the puck by Zach Bogosian, lower his shoulder and zip a backhand over goalie Chad Johnson.
"I wanted to get a quick shot off," Marchand said. "When I pulled it through, I just tried to get Bogosian's stick out of the way and get a shot off, so luckily it found the net."
Marchand has scored in seven of Boston's last eight games to raise his season total to 23.
"He's been really good," Bruins coach Claude Julien said. "Tonight he wasn't just good scoring, he was good everywhere; he was all over the ice. When he plays like that he becomes one of the good players around the league, no doubt."
Spooner had the lone goal in the shootout, and Tuukka Rask denied Brian Gionta, Evander Kane and Ryan O'Reilly.
Rask made 26 saves for the win.
"It was a very tight game right from the bat," Rask said. "We had more shots than they did, but it was an up-and-down game. You really had to fight for every inch on the ice there."
Kane and Sam Reinhart scored for the Sabres.
Buffalo had a two-goal lead for 58 seconds early in the second period before Spooner backhanded his own rebound past a prone Johnson to make it 2-1.
The Bruins carried that momentum past the midway part of the period, and Johnson was forced to make a pair of in-tight stops on Jimmy Hayes.
"For the most part it was a pretty good game for us," Spooner said. "Second period I thought we played one of the best of the year. We attacked a lot and that was good to see."
Jack Eichel's giveaway at the Boston blue line sent the Bruins on an odd-man rush, but Johnson swung his leg to make a backdoor stop. At the other end, Rask scooped up Jamie McGinn's rebound.
Boston had two prime chances to beat Johnson in the first 30 seconds of the third, but Zdeno Chara took a tripping penalty moments after Patrice Bergeron tipped a shot past Johnson but wide of the net.
Marchand tied it seconds after Boston killed the penalty, dangling Bogosian on the way to roofing an odd-angled backhand over Johnson at 2:44 of the third.
"It didn't surprise me," Johnson said. "When he comes down the wing like that, it rolls off his stick and is a goal."
Johnson stuffed Hayes' attempt with his left arm midway through the third.
Eichel came close to restoring Buffalo's lead when he carried the puck deep into the slot before firing a wrist shot high and wide of the net.
Kane took a slashing penalty in overtime, and Johnson spread out in the crease to make a low save of Bergeron's point-blank snap shot.
"It was just a shot to the net," Johnson said. "I know Bergeron had a set play there where he grabs it, tries to turn and spin it."
It was Rask's turn to shine when Bergeron gave Buffalo its own overtime power play 2:50 in.
"Chad made a couple of great saves and that's how it usually goes," Rask said. "The other team gets a penalty, too. We battled through it."
The Bruins killed off an early penalty in the first period, but Buffalo kept applying pressure. Johan Larsson drifted into the slot and wristed a hard shot toward the right corner, but Rask waffled the puck out of play.
At the other end, Matt Beleskey took a high, hard shot of his own that Johnson pushed wide of the net.
Kane fed Gionta on a 3-on-1 only to see the Sabres captain ring a shot off the right post, but Buffalo found the rebound. After a few more passes, Kane finished off Gionta's feed to make it 1-0.
The Sabres doubled their lead when Reinhart scored 47 seconds into the second. Mark Pysyk's point shot through traffic picked up a screen from Chara and changed directions to beat Rask.
NOTES: The teams play again Saturday night in Boston. ... Buffalo scratched defensemen Mike Weber and Carlo Colaiacovo.