D'Agostini, claimed off waivers from the Pittsburgh Penguins on Nov. 27, scored his first goal of the season when he put a loose puck past Devils goalie Cory Schneider.
"I felt like I was due for the last month or so," said D'Agostini, who played 13 games for the Devils during the 2012-13 season. "That's hockey sometimes. Sometimes they'll fall for you and sometimes you've got to wait and work for them. It was good to contribute and help the team win."
The Sabres extended their home point streak to seven games (6-0-1).
"We've got to learn to translate that on the road," D'Agostini said. "It's a long season, and a lot of those hard-fought games on the road we're just coming up short. I think we need to get better on the road, obviously, but taking care of business at home here is one thing. We've got a couple more games at home we need to take advantage of."
The loss was the Devils' first in their past seven in the second half of back-to-back games. New Jersey lost at home to the Chicago Blackhawks, 5-3, on Friday.
"The crowd maybe reacted well and we got some shots," Miller said. "The guys definitely feel the energy. It's important to hear that the crowd's behind you, and that's definitely one of those instances."
The Sabres took a 1-0 lead when Matt Moulson scored with 31 seconds to go in the second period. The power-play goal came when forward Tyler Ennis connected with Moulson on a pass in front of the net. Marcus Foligno was tied up with a defender, and Moulson used the distraction to put a loose puck over Schneider's shoulder for his 14th goal of the season.
"We haven't been getting many goals so they more than likely are going to be pretty ugly," Moulson said. "So we're fine with that and we need to keep doing that. Get pucks to the net, get guys driving to the net and get those dirty goals."
The Devils had a goal disallowed at 7:02 of the third period because of an injury stoppage after Buffalo's Tyler Myers hit New Jersey forward Dainius Zubrus with an illegal check to the head that left Zubrus down on the ice. Devils forward Michael Ryder put the puck in the net, but the officials ruled they blew the whistle before that happened.
"We were told that the referee in the neutral zone blew the whistle because of the injury to Zubrus," Devils coach Pete DeBoer said. "I don't know, I didn't hear one, but he said it was blown. I also wondered why that wasn't a five-minute major but I didn't get an explanation for that."
With Linus Omark already serving a too-many-men penalty, the Devils tied the game on the 5-on-3 power play when Ryder put a loose puck past Miller at 7:46. The Devils squeezed in on the Sabres defense and passes from forward Travis Zajac and defenseman Marek Zidlicky helped set up Ryder's 13th of the season.
"I thought we stuck with it," DeBoer said. "At the end of the day, we've got to finish. Henrique had a breakaway, [Mike] Sislo had a breakaway, we had some 2-on-1 opportunities. We've got to cash in."
D'Agostini's game-winning power play happened because Zubrus took an interference penalty on Myers at 10:03 of the third.
"You can't retaliate. [Zubrus] knows that," DeBoer said. "I think it's too easy a target to pin the loss on him. I think the loss is pinned on the fact we couldn't score 5-on-5. Breakaways, some 2-on-1s, we've got to finish some of those. Credit to their goalie, but we've got to find a way to score 5-on-5."
The Sabres power play went 2-for-5.
"It was a good feeling to get a couple on the power play tonight, and it was just a matter of taking the puck to the net," Myers said. "Both goals we had a guy take the puck in and we had guys crashing and banging away. It was simple, and that's what we have to do if we want to score."
Miller saved 21 shots; Schneider stopped 20.
"Ryan, quietly, I thought he was sensational again," Sabres coach Ted Nolan said. "A couple of those saves, I think Henrique tipped the puck on top of the circle, not too many goaltenders would be able to read that and see that. He made a great save that kept us in the game, and our power play was clicking here tonight."
The Sabres host the Carolina Hurricanes on Tuesday. The Devils return home to play the Philadelphia Flyers, also Tuesday.