Niskanen and the Penguins helped ruin the return of Nashville goalie Pekka Rinne in his first game since Oct. 22 following an E. coli infection in his surgically repaired left hip.
Chris Kunitz scored a goal, and Sidney Crosby had three assists to add to his NHL-leading point total. The Penguins have not lost more than three straight this season.
Patric Hornqvist scored for Nashville, which has lost two consecutive games. Rinne made 16 saves.
The Penguins took the lead for good during a power play after David Legwand was called for hooking Kunitz. Crosby found Niskanen for a slap shot that went under Rinne's glove.
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