Oxford made it three wins on the trot in League One after beating Barnsley 3-1 at Oakwell.
Cameron Brannagan scored an early penalty to put Oxford in front and Jordan Williams’ own goal made it 2-0 just before the hour.
Devante Cole pulled a goal back for Barnsley with 20 minutes left but Tyler Goodrham sealed the points for the improving visitors late on.
Oxford, who started the season with a 2-0 defeat at Cambridge followed by a 5-1 Carabao Cup mauling by Bristol City, came into the game on the back of wins over Carlisle and Derby and they needed just eight minutes to take the lead here.
Marcus Browne was fouled by Mael de Gevigney inside the area and Brannagan slotted home from the spot.
Barnsley went in search of an equaliser but Andy Dallas skewed his shot off-target from a great position and Nicky Cadden fired just over.
Oxford also had their chances and Mark Harris and Stanley Mills both shot straight at Liam Roberts in the Barnsley goal before Adam Phillips was denied by James Beadle at the other end.
Oxford increased their lead 10 minutes after the re-start. Mills made a surging run down the right, reached the byline and sent over a low cross which Williams attempted to clear but succeeded only in turning the ball into his own net.
Barnsley were given a lifeline in the 70th minute when Cole pulled a goal back with a header from a Cadden corner but Goodrham ensured it would be Oxford celebrating the win after being set up by Gatlin O’Donkor.
