A 14th-minute goal from midfield man Matt Sparrow did the trick, with Oxford only staying in the game thanks to the heroics of goalkeeper Ryan Clarke.
Showing few signs of nerves, Scunthorpe dominated much of the first half after 23-goal leading marksman Sam Winnall tested keeper Clarke from close range in the opening minutes.
They took the lead in the 14th minute when Sparrow forced his shot from 10 yards past Clarke after excellent work down the left by Paddy Madden and Michael Collins had opened up the Oxford defence.
Scunthorpe went close again four minutes later when Madden raced into the box but at full stretch saw his shot deflected away by keeper Clarke.
Oxford had only one real sight at goal when Alfie Potter found himself in space on the right of the box but he could not find his finishing touch, dragging his shot wide of the far post.
Scunthorpe again had all the second half efforts, but could not find a way past Clarke who was man of the match for the visitors.
First he got down well to keep out a fierce shot from midfield man David Syers. Then he produced a great reaction save to turn over a close-range header from centre-back Niall Canavan following a corner.
Finally, he went full length to turn away a free-kick from the edge of the box by Terry Hawkridge.
Oxford, whose play-off hopes are fading fast, offered little threat as an attacking force, with some closing pressure being too little, too late.
- Sports & Recreation
- Matt Sparrow
- Ryan Clarke
- Paddy Madden