Oxford maintained their eight-point lead in the Blue Square Premier after seeing off a strong Crawley challenge.
Adam Chapman gave the home side the lead with a breathtaking free-kick from the edge of the Crawley area.
But, when Mark Creighton was penalised, Crawley levelled from ex-Oxford striker Jefferson Louis's deflected free-kick.
Full-back Steven Kinniburgh then lobbed Crawley keeper Simon Rayner before Jack Midson rounded him to tap in the third after he spilled Matt Green's shot.
Crawley assistant manager Payl Raynor told BBC Sussex:
"We were undone by a goalkeeping error, if I'm being absolutely honest.
"Simon's been absolutely magnificent over the past few weeks. But, by his own admission, he's come straight in after the game and apologised to the boys.
"That's the type of character he is.
"We did work very hard. I thought first half we were very good and the crowd were getting a wee bit frustrated.
"I'm just very disappointed because, at half-time, we thought we could not only get a draw but actually win the game."
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