THREE second-half goals secured three points for the U's at Dagenham this afternoon.
The U's started the first half brightly, but it was the hosts who took the lead on 20 minutes, Luke Howell nodding past Chris Dunn.
Jayden Stockley had the best chances of the half for United, heading into O'Briens hands and dragging a shot wide on 43.
HT: Dagenham 1-0 U's
The U's once again started the half brightly and leveled matters through Ryan Donaldson on 54 minutes. Harrison Dunk was fouled 20 yards out and up stepped Donaldson to curl home the free-kick.
United took the lead on 61 minutes, Ryan Donaldson's corner found Michael Nelson, who planted his header past O'Brien to make it 2-1.
On 77 minutes Ryan Bird made it 3-1. After good work from Liam Hurst, Bird got on the end of a looping ball into the box and the ball ended up in the back of O'Briens net.
The hosts pulled a goal back on 83 but the U's held firm to secure the points, Chris Dunn making a fantastic fingertip save in the dying moments.
FT: Dagenham 2-3 U's
ATT: 2074 (770)