Cheltenham Town made it seven away wins in a row and inflicted a fifth consecutive defeat on Oxford United.
Sido Jombati gave the Robins the lead with a left-footed cross-shot from the right-hand side.
Visiting centre-back Alan Bennett hit the bar before Oxford had Liam Davis sent off for a second booking.
James Spencer's tapped home for 2-0 and Peter Leven's late free-kick gave Oxford hope before Kaid Mohamed's deflected free-kick sealed it.
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Oxford United boss Chris Wilder told BBC Radio Oxford:
"I thought the way we responded after going 2-0 down was magnificent. We showed real spirit.
"We're looking at getting Michael Duberry, Alfie Potter and Tom Craddock back soon, so that will be a real boost to us.
"Cheltenham are an excellent side and they're on great form."
Cheltenham Town manager Mark Yates told BBC Gloucestershire:
"It's a tough place to come. They've got a few injuries at the moment so it was probably a good time to play them.
"It was a deserved victory as they put in a really spirited performance in the second half, but we're disappointed that we conceded a goal.
"I don't want to single anyone out, one to 11 and the subs were all good, and there were some really good performances."