Leon McKenzie grabbed the winner as Northampton ended Oxford's impressive run with a 2-1 victory in a pulsating game at Sixfields.
The striker maintained his impressive goals-per-game ratio with his seventh strike in just 11 starts for Cobblers, who held on to pick up three vital points against the in-form visitors.
Andy Holt had put Northampton in front just before half-time before Tom Craddock levelled early in the second half.
James Constable twice came close for Oxford while the impressive Harry Worley volleyed over. But Northampton gradually came into the contest and Nathaniel Wedderburn tested Ryan Clarke with a fierce drive which he turned round the post but from the ensuing corner the outstanding Holt headed Cobblers in front.
Oxford were level within two minutes of the restart when Asa Hall's shot found Craddock, who turned the ball home from close range with Northampton appealing for offside.
Constable missed a great chance to put Oxford in front before McKenzie grabbed what proved to be the winner in the 67th minute. The inspirational Holt produced a perfect cross for McKenzie to head home from close range.