Ciaron Brown hit a late winner as Oxford came from behind to beat Fleetwood 2-1.
Kyle Joseph had scored their equaliser seconds after coming on, cancelling out Brendan Wiredu's strike at the end of the first half.
And Brown forced in a second goal at the death to give his side an unlikely win.
Fleetwood had dominated the first half but looked like turning around on level terms after goalkeeper Simon Eastwood had kept his side in the game.
He denied Cian Hayes and Promise Omochere with early chances. And Admiral Muskwe's shot was blocked late in the half as Oxford struggled to hold out.
But as the break loomed Muskwe found Wiredu on the edge of the box and he drilled the ball into the bottom corner.
Hayes had a chance to double the lead soon after the restart when Josh Vela played him in but he shot straight at Eastwood.
And, immediately after replacing Yanic Wildschut just after the hour mark, Joseph weaved his way through the defence to score Oxford's leveller.
Fleetwood should have regained the lead when Omochere somehow put his finish over at point-blank range.
And, with the 90 minutes up, a goalmouth scramble led to Brown prodding in a dramatic winner.