A stunning Kemar Roofe free kick was the difference between the two sides, as Oxford United won by a single goal at Victoria Road.
The Daggers are still without a win at home this season following this defeat.
It was unchanged line-up for the hosts following their midweek win in the FA Cup at Morecambe.
Kyle Vassell kept his place up top after scoring a brace at the Globe Arena while Joss Labadie
wore the armband in the absence of Andre Boucaud
It was Labadie who went close to opening the scoring, being denied by Benjamin Buchel after a great half volley from the edge of the box in the ninth minute.
Twelve minutes later, Jamie Cureton
headed wide from a good position following a cross into the box from Ashley Chambers
Cureton went close again in the 42nd minute but the striker fired over from six yards after being played in by Josh Passley
Liam O’Brien was called upon to keep the scores level in the 51st minute, denying John Lundstram who struck from the edge of the area.
The Daggers stopper had to be at his best 16 minutes later to stop Alex MacDonald from scoring from just inside the box.
Kemar Roofe then hit the bar for Oxford before Cureton forced Benjamin Buchel into action from a corner in the 72nd minute.
Roofe did find the back of the next 13 minutes later with a brilliant free kick for the visitors.
Daggers: O’Brien; Passley, Nosworthy, Dikamona, Widdowson; Chambers (Mulraney 74), Labadie, Dunne, Hemmings (Jones 88), Cureton (McClure 86), Vassell
Unused subs: Cousins, Raymond, Ferdinand, Obileye
Attendance: 1,980 (including 685 Oxford fans)
Referee: Kevin Johnson