Larsson buried the 2-on-1 feed from Evan Rodrigues at 5:43 in the second period. They pushed for a third goal for the next 30-plus minutes, to no avail.
The chances were there. Rask's 26-save night included a glove save to rob Remi Elie on a 2-on-1 rush in the second period and a point-blank stop on a tip from Elie in the third. Jason Pominville saw a deflection drift inches wide of the net.
Hutton made 39 saves for Sabres, including 17 stops in the third period. They felt they controlled they quality of chances against in those final 20 minutes despite the high volume of shots.
"I can't fault our effort and the way we played tonight," Sabres coach Phil Housley said. "If we continue to play like that, we're going to be on the right side of things."
The call against Ristolainen, which came on a knee-to-knee collision with Pastrnak in the corner, was preceded by a no-call on a play in which Bruins defenseman Zdeno Chara had an arm wrapped around Conor Sheary along the boards.
DeBrusk tied the game with a tip of a shot from the point by Torey Krug, the only blemish on an otherwise stellar night from the Sabres' penalty kill.
"Yeah, that was a pretty tough call at the end," Rodrigues said. "They were kind of letting things go, I thought, from the last half of the third. It's a tough call and nice tip-in. That's one that got away from us. But at the same time, if we keep playing like that, we'll win some games."
Housley declined to comment on the officiating.
"I don't really want to get into that," he said. "We just try to control what we can control. There's going to be calls for us and there's going to be calls against us that we're not going to agree on. That's what the game gives you. You have to still stay focus on the task at hand and focus on your next shift."
The Sabres had a chance to win the game on their own power play overtime, but generated just one shot on goal. Kuraly buried his own rebound on the rush for the winner.
The Sabres' lead over the Bruins for third place in the Atlantic Division is down to two points, with the teams set to meet for their season finale in Boston next Saturday. The Sabres will play two games at home in the meantime, against the Islanders on Monday and the Panthers on Thursday.
They'll look to rebound from one that got away.
"It's unfortunate we took a penalty at the end," Scandella said. "I thought we played a great game collectively. It's too bad that we lost this one. We should've won."
