Niemi turned aside 12-of-13 shots in the third period, allowing only a power-play goal to Henrik Zetterberg as the second-seeded Sharks won their second straight home game to start their Western Conference semifinal series.
Ian White scored on a first-period power play and Niclas Wallin found the net 1:39 into the final frame for San Jose, which will have the momentum when the series switches to Detroit for Wednesday's Game 3.
San Jose ousted Detroit in five games in last year's conference semifinals.
Jimmy Howard stopped 35-of-37 shots in goal for the third-seeded Red Wings.
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