Oxford made it back-to-back league wins for the first time this season as they shocked Preston with a 3-1 win at Deepdale to move out of the relegation zone.
Michal Helik prodded the relegation-threatened outfit ahead in the fourth minute before Milutin Osmajic's 12th-minute equaliser.
Will Lankshear's improvised 54th-minute finish gave Matt Bloomfield's men a deserved lead and Ciaron Brown's header seven minutes later sealed the points.
Oxford jump up to 21st, ahead of Leicester and West Brom ahead of the weekend fixtures, while Preston are now five games without a win as their play-off hopes continue to disappear.
Paul Heckingbottom made a number of positional changes, including a shift to a back four with Andrew Hughes in an unorthodox left-back role, which perhaps explained their disjointed display against relegation-threatened opponents.
Preston's form has dropped off a cliff of late and they were stung early on here as Helik had to time chest down Cameron Brannagan's free kick and poke a finish past an exposed Dai Cornell as defenders just stood and watched.
Brown should have doubled Oxford's lead inside 10 minutes but headed wide and Preston soon made him pay as an unmarked Osmajic nodded past Jamie Cumming having landed on the end of a pinpoint Ben Whiteman delivery.
But the spirited visitors were not to be deterred and, within five minutes, Jamie Donley and Stanley Mills fired narrowly wide from just inside the box with Will Lankshear also seeing a goal-bound shot blocked by Lewis Gibson.
Callum Lang did keep Cumming's gloves warm with a 23rd-minute whipping free-kick after Osmajic was brought down by Brown - a reprieve from the visiting storm.
Eventually, the hosts did get a grip of the match - having a series of half-chances - but nearly fell victim to overplaying at the back after Donley seized on a loose ball and slipped Lankshear in on goal, who fumbled the opportunity with a poor first touch that allowed Cornell the chance to get his body in front of the attempted finish.
Oxford took the lead at the start of the second half with Lankshear diverting Stanley Mills' drilled strike from range into the corner following Ben Whiteman's half-clearance.
The U's were in dreamland and that dream began to soar just a minute after the hour as Brown got himself forward to emphatically head home a third, latching on to Helik's flicked header from Myles Peart-Harris' teasing long throw.
Brannagan already had an assist and smelled blood minutes on from the third goal, forcing Cornell into an awkward low save from 25 yards.
Jeers were ringing around Deepdale as the home faithful watched those in yellow run rings around players who were chasing a play-off spot not too long ago.
Preston's Paul Heckingbottom: "There were no surprises in how they set up, especially away from home - defend deep, deny space and be a threat on counters and set-plays.
"That's why I'm so disappointed because if we're going to concede three goals in the manner that we did, we're not going to give ourselves a chance in games.
"I feel at the minute we're a soft touch when we're defending in our box and that's happened three times.
"(Earlier in the season) we were like a brick wall at times, whether that be denying the ball from getting in the box (or blocking it) if it did come in. Everything else between both penalty boxes is just smoke and mirrors. It's propaganda."
Oxford's Matt Bloomfield: "I think the results are important but, if we just focus on that, we'll forget that it's the performance that takes you to the result. I thought we played with real energy, freshness and enthusiasm tonight.
"We were disappointed not to be ahead at half-time. We adjusted things ever so slightly at half-time in terms of our tactical approach to our defensive work in the second half.
"The lads took the opportunities when they came along and were able to see the game out. A really good mentality to see that game out in the second half.
"It was a real team effort, a real squad effort and we're going to need every single one of our players between the seasons to contribute."
