Senators score 5 in the second, beat Penguins 6-4
Daniel Alfredsson scored his 398th NHL goal and added two assists, and Erik Karlsson also had three points.
Colin Greening scored 25 seconds into the second, and Zenon Konopka netted Ottawa's fifth goal of the period with 5.7 seconds left, increasing the Senators' lead to 5-3 just 4 seconds into a power play.
Karlsson recorded his 100th point with his third assist of the period on Konopka's goal.
Pittsburgh's Steve Sullivan had a goal and two assists as the teams combined for eight goals in the middle period after a scoreless first. Matt Niskanen and Evgeni Malkin scored power-play goals 1:07 apart to draw the Penguins even at 3.
Chris Kunitz scored with 1:02 left in the third.