Josh Payne scored his first Oxford goal to get Chris Wilder's men back to winning ways after two defeats in a row with a 3-1 victory over Northampton.
The midfielder, who is on a three-month loan from Doncaster, curled in a brilliant free-kick from nearly 25 yards on the stroke of half-time.
Oxford were given the perfect start with winger Alfie Potter firing home left-footed in only the fourth minute.
It came at the end of a fine move involving Payne, Ben Purkiss and James Constable, whose right-wing cross found its way to an unmarked Potter eight yards out.
But Northampton, themselves looking to bounce back after four straight defeats, were back on level terms within 12 minutes.
Liam Davis got free on the left to chip a cross to the far post where Leon McKenzie headed powerfully home for his fourth goal in two games.
After Payne's free-kick had restored Oxford's lead, Cobblers pushed hard for a second goal in the second half, and Kevin Thornton missed a golden chance, shooting wide on the turn from close range after 66 minutes.
But a stoppage-time penalty, converted by Tom Craddock, sealed their fate. John Johnson brought down Simon Clist, and was red-carded.
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