Chiasson snapped a third-period tie and lifted the Dallas Stars to a 3-2 victory on Monday night.
Stars coach Lindy Ruff earned his 600th NHL win, and he got it against his former team. Ruff's first 571 wins came with Buffalo.
"It means I'm on my way to 700, hopefully," Ruff said. "It means that I've had a lot of good players and good teams. Those wins belong to those players."
Chiasson's goal was his first in 13 games, and he wasn't the only player who broke a scoring drought. Alex Goligoski put Dallas ahead briefly 2-1 with his third goal this season after 48 games without one.
"He has looked refreshed and energized," Ruff said of Chiasson. "He needed one to go in."
Jordie Benn hadn't scored until he tied the game 1-1 in the second period with his first goal in 12 games. He knew what a victory would mean for Ruff.
"Obviously, it's huge to get that win for him," he said. "He's a very decorated guy, a great guy and a great coach."
The Stars opened a two-point lead over their closest pursuers for eighth place in the Western Conference. Dallas (29-22-10) has 68 points. Winnipeg and Vancouver both have 66.
Tyler Ennis scored twice for Buffalo, with Matt Moulson assisting on both goals. The second got the Sabres even at 3:23 of the third.
Ray Whitney had two assists for the Stars after moving during the game on to a line with Jamie Benn and Tyler Seguin, Dallas' two leading scorers.
Chiasson, a rookie forward, was frustrated because Sabres goalie Jhonas Enroth stopped six of his team-high seven shots on goal.
Then, at 10:25 of the third period, Chiasson skated in front of Enroth and deflected Jamie Benn's slap shot from the blue line into the net for the winning goal.
What Chiasson couldn't do with his stick, he accomplished with his leg.
"Sometimes you're going to need help from other people, but we need Jamie," he said. "Look at the first goal, Jamie was right there (screening Enroth). And then on the last one, his shot hit me in the shin guard."
Enroth complained, but the goal stood.
"Something happened there you couldn't really see on the replay," the goalie said, "but the ref told me it was (teammate Mike) Weber that kind of got his stick in my glove or whatever happened there."
Chiasson said that the Stars' 19-day Olympics break helped him.
"I went through a phase where I couldn't see the light out of the tunnel," he said. "It seems like the break came at the right time. I put some weight back on, and I felt rested."
Enroth made 36 saves, and Dallas' Kari Lehtonen had 21.
"The first couple periods, I didn't think we were in the game at all. If it wasn't for Jhonas, I don't think that the score would have been as close as it was," Sabres coach Ted Nolan said. "I thought in the third period we played a bit better. We took a bad penalty, again. They capitalized, and that was the difference."
Dallas dominated the first period everywhere but on the scoreboard as the Sabres took a 1-0 lead.
The Stars recorded 14 of the first 17 shots, but failed to score on three power plays despite putting seven shots on goal.
Dallas nearly gave up a short-handed goal on the third advantage, but Matt D'Agostini's shot hit the crossbar.
The Sabres scored on their next shot. Drew Stafford skated in on the left side, and when Dallas' Trevor Daley slid on the ice to try to block a shot, Stafford passed the puck across to Ennis, who scored at 17:17.
Dallas outshot the Sabres 16-5 in the period, which ended with Enroth stopping Chiasson's close-range backhand.
Chiasson put a team-high four shots on goal in the first, including some of the Stars' best chances. Enroth had stopped Chiasson's slap shot on Dallas' first power play, as well as two slap shots by Cody Eakin.
The Stars tied it 1:30 into the second period when Jordie Benn sent a slap shot from the left point past his brother Jamie's screen, and past Enroth.
Six seconds before the period ended, Gologoski scored.
Ryan Garbutt deflected Trevor Daley's slap shot off the post. Shawn Horcoff gathered in the rebound and sent a backhanded pass across the goalmouth to Goligoski, who scored into the left side of the net.
The Stars had a 12-9 advantage in shots, for a two-period total of 28-14.
Buffalo tied it when Moulson's shot went over the net but bounced back off the glass to Ennis, who tucked the puck into the lower right corner.
The loss ended a season-best three-game winning streak for Buffalo (18-35-8).
NOTES: The Stars were 1 for 26 on power plays in their previous seven games. ... Eakin left the game with 3 minutes remaining, but Ruff said there was no serious injury. ... Jamie Benn has six goals, nine assists in his last 11 games. ... Enroth has stopped 101 of 110 shots in his last three games. ... In his last four games against Dallas, Moulson has six goals, two assists. ... Buffalo was penalized six times; the Stars only once. "I just think it was typical last-place calls to a playoff-team calls, and that's just the way life works once in a while," Nolan said.