Selanne scored twice in the second period (once on a penalty shot) and again in the third en route to a five-point night for the Ducks, who rebounded from an early 2-0 deficit and swept the season's series from Colorado.
Cam Fowler added a goal and an assist, Jason Blake tallied and Saku Koivu added a pair of assists as the Ducks retained their hold on the seventh seed in the Western Conference playoff standings with six games remaining.
Ray Emery turned aside 31-of-35 shots to earn the victory.
Matt Duchene notched a goal and an assist, Milan Hejduk collected three helpers and Brian Elliott made 37 saves for the Avalanche.
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