The Penguins gained a small measure of revenge for last season's conference final sweep at the hands of the Boston Bruins with a 3-2 win over the same opposition.
A high-scoring final period saw Brandon Sutter and Jussi Jokinen put Pittsburgh three goals to the good and while Jarome Iginla pulled a late goal back, the Penguins opened up a seven-point lead in the Metropolitan Division.
Paul Ranger's unassisted late goal rounded off the Leafs' 4-2 win over the Calgary Flames, which was built around 41 saves from Jonathan Bernier.
They lead the Atlantic Division by four points from Tampa Bay, Montreal and Detroit, the Red Wings beating the Vancouver Canucks to join the pack.
Daniel Sedin gave Vancouver a first-period lead but goals from Daniel Alfredsson and Tomas Tatar in the second were enough to earn Detroit a first win in five.
The Los Angeles Kings needed overtime to see off the San Jose Sharks 4-3 in the night's other game, Anze Kopitar with the decisive power-play goal.