Substitute Barry Corr scored late on as 10-man Southend came from behind to win at Oxford.
Corr turned in Ben Coker’s cross with eight minutes left, just after two U’s efforts had been cleared off the line.
Callum O’Dowda’s low finish gave Oxford the lead, before David Worrall headed an equaliser from a Coker cross.
After Southend’s Gary Deegan was sent off, Sam Long headed his first Oxford goal, but Joe Pigott nodded in to make it 2-2 before Corr struck.
Shrimpers boss Phil Brown was sent to the stand late on for persistent encroachment onto the pitch.