Asa Hall scored twice to give Oxford victory at Accrington and lift the U's up to sixth position in League Two.
The hosts nearly went ahead but defender Jake Wright cleared Jamie Devitt's volley off the goal-line.
Hall grabbed his first goal two minutes later when Accrington failed to clear and he collected a loose ball and smashed a low shot home from 12 yards.
Bobby Grant and Padraig Amond missed chances for an equaliser, before Hall headed in from James Constable's cross.
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Oxford United manager Chris Wilder told BBC Radio Oxford:
"I had a bit of a bark at the players at half-time because I thought we could do a lot more, and when we did we scored at a decent time.
"It's not easy coming here, even though they had a few injury problems at the back, the mentality of the players is such they always give it a go and they're a dangerous outfit.
"The result is the main event, and to get four points out of six from two difficult away games is a real good effort. Goals change games, the first was very well-timed and the second was a great goal."