Penguins defenseman Kris Letang, who returned after missing five games with an upper-body injury, scored a power-play goal 1:27 into the third period to make it 4-1. Shortly after an unsuccessful penalty shot attempt by Scott Wilson, Patric Hornqvist scored at 7:14 for a 5-1 Pittsburgh lead.
"We were playing well. It was 2-0 before they scored that goal," Letang said. "We knew we had the momentum, and they caught us with a long shift on the penalty kill and scored. We came back right where we left off after they scored."
The Penguins (7-2-1), who have outscored opponents 12-5 in the third period, have won four games in a row.
The Ducks (4-5-2) have lost two of three and have been outscored 9-1 in their past two home games.
Each loss has come after an emotional win the prior game. The Ducks defeated the Los Angeles Kings 4-0 on Tuesday. Before losing 4-0 to the Columbus Blue Jackets last Friday, they won 6-1 against the Nashville Predators, who eliminated them from the 2016 playoffs, on Oct. 26.
"That's what we're just banging our head against the wall over right now," Anaheim coach Randy Carlyle said. "We're looking at it and saying, 'Why, why, why?' and the answer to it isn't right at the tip of my tongue. I wish I had that answer."