Dagenham's National League survival hopes were hit after Will Davies netted a last-minute equaliser to salvage Sutton a draw.
The Daggers missed a glorious chance to go ahead in the opening 30 seconds as Ryan Hill had a penalty saved by Jack Sims after a handball.
Dagenham did go ahead in the 64th minute as Josh Rees glanced a header into the path of Josh Umerah and the striker was on hand to nod home his seventh goal of the campaign.
But the visitors, now three points above the bottom four before the afternoon kick-offs, could not hold on with Davies heading home two minutes into added time.
Report supplied by PA Media.
