The Ducks moved within two points of Chicago for the best record in the Western Conference, although the Blackhawks have two games in hand.
Dallas, which has dropped three straight to fall out of serious playoff contention, did not score until Erik Cole tipped in a shot 2:48 into the third period.
The Ducks also defeated Dallas 4-0 Monday and the teams will play again Friday in Anaheim.
Fasth made 23 saves for the victory. Kari Lehtonen allowed four goals on 26 shots.
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