Alfie Potter scored a second-half leveller for Oxford at fellow play-off hopefuls Burton.
Adam Bolder gave the Brewers an early lead after a smart corner routine found him in space, his low shot just beating U's keeper Ryan Clarke.
Potter forced a fine stop from home custodian Ross Atkins before firing in an excellent strike after breaking through the home defence.
James Constable almost won it for the visitors but he shot just wide.
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Burton Albion manager Paul Peschisolido:
"We had so much possession and the style of football we played in the first half was absolutely magnificent.
"We got on the ball, we passed it and our movement was magnificent. We just attacked and attacked and attacked.
"If we had got the second goal then that game would have probably been finished.
"If it's only 1-0 in the second half then there is always that opportunity for a moment of brilliance and an equaliser and that is what happened."
Oxford forward Alfie Potter told BBC Radio Oxford:
"It was not the best first half from us, but the gaffer made some changes and it worked and in the end I think we were unlucky not to win it.
"The goal was long overdue, I've been missing a lot of chances, but in the end I could have had a couple. I'm glad to get one and hopefully it's the first of many. It was all instinct, I just put my foot through it.
"It was just one of those games, first half we couldn't get to grips with them but second half we were excellent."