Carter put the Penguins ahead 1-0 at 1:58 of the second period when a pass from Frederick Gaudreau redirected off his shoulder and past Houser's glove. Carter has scored nine goals in 14 games since being traded to Pittsburgh on April 12 after scoring eight goals in 40 games with the Los Angeles Kings.
Drake Caggiula had a chance to tie it on a breakaway at 16:05, but Lagace made a stick save on his wrist shot.
"They should have no confidence going into this building today giving up eight goals the other day," Sabres coach Don Granato said. "They came in that game from the drop of the puck and had confidence. That's progress."
Lagace preserved Pittsburgh's lead at 10:41 of the third period, using his left arm to turn away Victor Olofsson's one-timer from the low slot.
"It was great to see," Penguins defenseman Marcus Pettersson said." I don't think we had our sharpest game. We really relied on him from the get-go. We felt comfortable with him. He was calm and poised back there. I thought he did a great job."
NOTES:Pittsburgh and Washington can finish tied in points (77) and regulation wins (29). The Penguins would win the second tiebreaker, regulation plus overtime wins (34-32). ...Pittsburgh center Evgeni Malkin remained on the bench for the final 8:48 of the third period for precautionary reasons, Sullivan said. Malkin was playing his fourth game since returning from a lower-body injury that kept him out the previous 23 games. Malkin's point streak against Buffalo ended at 15 games (seven goals, 15 assists). It was tied for the second longest against the Sabres in their history, behind teammate Sidney Crosby, who had a 19-game streak (10 goals, 26 assists) from Dec. 29, 2007-Nov. 8, 2014. … Houser allowed eight goals on 34 shots Thursday. He was raised in the Pittsburgh suburb of Wexford, Pennsylvania, after moving from Youngstown, Ohio. … Penguins forward Colton Sceviour had one hit and one blocked shot in 9:33 in his 500th NHL game. … Granato, who was named coach of the Sabres after Ralph Krueger was fired March 17, said after the game he had not started to think about his future with Buffalo.