OXFORD United crashed to their heaviest defeat in almost two years as Burton Albion came out on top at the Pirelli Stadium.
The visitors were booed off by a section of the travelling supporters at the final whistle after slumping to a fourth defeat in five games.
Superb finishes from Calvin Zola and Jacques Maghoma gave the Brewers a 2-0 lead at the break.
Both players struck within 60 seconds of each other midway through the second half to make the game safe.
It inflicted the biggest league defeat on the U's since a 5-0 loss at Bradford City in October 2010.
United boss Chris Wilder began by changing formation from his favoured 4-3-3 to 3-4-3, with Daniel Boateng brought in as one of three centre backs.
Jake Forster-Caskey made way, suffering with a virus.
The visitors had the first sight of goal, on nine minutes, when Michael Raynes headed over at an Adam Chapman corner.
Burton went on to have a good spell and almost took the lead in bizarre circumstances.
An innocuous ball into the box almost caught out Ryan Clarke, who readjusted in time to parry the ball on the line.
The U's goalkeeper was beaten on 16 minutes, but the woodwork came to his rescue. Lee Bell's free-kick hit the defensive wall, but from the rebound Damien McCrory's effort rattled the crossbar.
Burton opened the scoring midway through the half thanks to a moment of brilliance from Zola.
Chesting a through ball, the striker spun and off-balance volleyed first-time over Clarke and into the net from 30 yards.
It was a stunning strike, but United recovered well.
They went on to control the game for 20 minutes, pinning Burton back.
But other than an Alfie Potter which flew wide of the post, they failed to open up the Brewers.
Instead the home side doubled their lead on the stroke of half time.
It was another smart finish, with Maghoma bending a shot from the edge of the area in off the crossbar, but unlike the first goal United were partly culpable, wasting several chances to clear the ball in the build-up.
Boos from the away end accompanied the half time whistle, but the visitors began the second half strongly.
Within seconds two substitutes combined, with Jon-Paul Pittman crossing for Tom Craddock, whose shot was deflected over.
The new faces saw United switch to 4-2-3-1, with Potter, Craddock and Pittman in behind Smalley.
Pittman in particular looked dangerous and one lashed shot was brilliantly tipped over by Albion goalkeeper Stuart Tomlinson.
It was as good as it got for United, as two goals in the space of a minute ended the game as a contest.
Wright was booked for bringing down Zola on the edge of the box and from the resulting free-kick Maghoma curled over the wall and into the net.
A section of away fans began singing "what a load of rubbish" and the chorus was still in full swing when Zola made it 4-0.
The big striker was allowed the time to control a cross and shoot past an exposed Clarke from eight yards.
United looked a beaten side and although they attempted to stick to their task, Burton cruised through the closing stages.
Tyrone Marsh came off the bench for the final seven minutes, so will be the only U's player to remember the game fondly.
United have little time to regroup, with a trip to Cheltenham Town coming up on Tuesday.
United: Clarke, Boateng (Pittman 46), Raynes, Wright, Batt, Chapman, Heslop, Capaldi, Rigg (Craddock 46), Smalley (Marsh 83), Potter.
Unused subs: Brown, O'Brien, Worley, Cox.
Burton: Tomlinson, O'Connor, Diamond, Holness, McCrory, Taylor (Dyer 55), Bell, Weir, Maghoma, Zola (Richards 75), Paterson (Corbett 57).
Unused subs: Atkins, Webster, Stanton, Kee.
Referee: Richard Clark Attendance: 2,389