Jed Lowrie added an RBI double and Kyle Blanks had a run-scoring single against Adam Warren to stretch Oakland's lead in the 10th, with Stephen Vogt coming through with a clutch pinch-hit double that tied the game at 2-2 in the eighth.
Moss' blast off Warren (1-3) helped the A's record their fourth straight victory and made a winner of Dan Otero (5-1) after he tossed a scoreless ninth.
The Yankees got a boost from Mark Teixeira in his return to the lineup, with the first baseman driving in both New York runs on a single and a solo homer after sitting five of the last seven games with wrist soreness. Warren faltered in the 10th, however, tagged for three runs and three hits while retiring just one batter, as the Bronx Bombers fell to 1-4 on their current homestand.
Both starting pitchers performed well while not factoring in the decision. New York's Hiroki Kuroda held the A's to a run and two hits over 6 2/3 sharp innings, with Scott Kazmir striking out a season-best 10 in 6 1/3 innings of two-run ball.