Belanger scored on the power play at 18:32 of the first period and his second goal gave Minnesota what turned out to be an insurmountable 4-1 lead at 12:28 of the second.
Boston got two goals from Marc Savard and one from Phil Kessel. P.J. Axelsson had two assists, and former Wild goalie Manny Fernandez allowed all four goals on 26 shots.
The clubs had not met since March 8, 2007, when the Wild won 2-1 at Boston.
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