Crosby's 12th goal of the season was also the 250th of his career, and the Penguins' captain also had an assist. Chris Kunitz had two goals and an assist, Evgeni Malkin had a goal and two assists, and James Neal added two assists.
Jeff Zatkoff, playing for the first time since Nov. 2, stopped 32 shots in his fourth NHL start.
Thomas Vanek scored twice for the Islanders in his first game after missing five with an upper-body injury. Vanek has three goals and two assists with New York since being acquired from Buffalo in October. Colin McDonald also got his second of the season for the Islanders.
Kevin Poulin made 30 saves for the Islanders.
CANADIENS 3, CAPITALS 2
Desharnais, whose scoring drought even attracted the attention of Montreal's new mayor, perched in front of the net to redirect Josh Gorges' drive in the first period. The goal stood after a video review to determine whether Desharnais had scored with a high stick.
Ovechkin scored on a last first-period power play and again in the third period to give him an NHL-leading 19 goals.