Oxford Utd 0
Scunthorpe Utd 2
(Burton 10, Syers 74)
A disjointed Oxford United crashed to a second home defeat in the space of four days as in-form Scunthorpe United snatched all three points.
The margin of victory could have been wider, as the visitors wasted clear-cut chances before making the game safe.
Deon Burton headed the Iron into a tenth-minute lead and the experienced striker had a penalty saved by Ryan Clarke before half-time.
United struggled and after the break their errors became more and more regular.
Burton let them off the hook, missing when through on goal after a Jake Wright mistake, but it did not stir the home side.
The second goal did eventually come when David Syers pounced on a sliced clearance from Johnny Mullins and coolly beat Clarke.
Deane Smalley, who had given away the penalty in the first half, had a chance to make amends from the spot when Constable was fouled late on, but his effort was saved.
It completed a miserable afternoon for the home side, who lost successive league games for the first time this season.
Smalley came in for the suspended Dave Kitson in the only change to the U's starting line-up from the 3-2 defeat to Plymouth Argyle on Boxing Day.
After a cagey opening, Ryan Williams got the home fans off their seats by winning the ball in his own half and setting off on a run.
The on-loan Fulham winger burst all the way into the Scunthorpe area, where he was tackled on the verge of pulling the trigger.
Scunthorpe had hardly strung two passes together, but in the tenth minute they pounced on a defensive mistake to take the lead.
United striker Deane Smalley fires his late spok-kick goalwards, but Scunthorpe goalkeeper Sam Slocombe pulled off an excellent save
Wright sloppily gave the ball away and it was quickly spread wide for Marcus Williams, who crossed to find Burton unmarked to head into the net.
A bad start was the last thing United needed in the wake of the Plymouth defeat, but they almost found a quick response.
David Hunt's long throw found its way to Sean Rigg at the back post, where the winger prodded tentatively over the bar.
Neither side kept the ball well in a scrappy opening half hour.
Scunthorpe surrendered possession cheaply several times, but they were let off the hook by a lack of quality on the final ball from their hosts.
Iron goalkeeper Sam Slocombe made a routine save from Rigg, before he and teammate David Mirfin both scrambled to keep out James Constable.
The hosts were building some momentum, but as in the Plymouth game they shot themselves in the foot by conceding a penalty for handball in the 39th minute.
Smalley was the culprit this time and the slap of the ball hitting his hand bounced around a stunned Kassam Stadium.
Burton stepped up, but Clarke dived to his right and parried the ball, which was fired wide on the follow-up.
The goalkeeper came to the rescue again shortly afterwards, racing out of his area to clear as Hakeeb Adelakun chased a through ball.
United winger Sean Rigg rides this challenge to knock the ball forward
On the stroke of half-time a section of home fans were celebrating an equaliser as Johnny Mullins rippled the net with a header. Unfortunately it had passed the wrong side of the post and hit the side netting.
United had looked laboured, though, and it did not improve when the second half began.
Smalley and Constable were forced to feed on hopeful balls launched forward and when they did manage to win a flick-on all too often the strikers were too far apart.
Asa Hall stung Slocombe's palms from virtually the same spot 25 yards out that he had scored against Plymouth.
It was not the cue for something more sustained from the hosts, as Scunthorpe instead exploited their mistakes.
Midway through the half Wright was caught dithering in possession by Syers. The ball rebounded to send Burton clean through, only for the veteran striker to shoot off target.
The home fans became restless as their side became increasingly disjointed.
A second goal looked inevitable and it duly arrived 18 minutes from time.
Mullins, who had been one of the few positive performers, mis-kicked a ball over the top, gifting Syers a free run on goal to lob a stranded Clarke.
The game looked over, but seven minutes from time Constable gave them a lifeline.
The striker outmuscled Mirfin in the area and was brought down by Slocombe, who was booked.
Smalley assumed the penalty duties, but just like Burton in the first half his effort from 12 yards was saved.
United had a late flurry which saw Slocombe save well from Tom Newey, but it was too little too late for the home side.
Oxford Utd (4-4-2): Clarke, Hunt, Mullins, Wright, Newey, Williams, Hall, Rose, Rigg, Smalley, Constable.
Subs used: O'Dowda (Rigg 56), Ruffels (Rose 65), Davies (Ruffels 90).
Unused subs: Crocombe, Long, Raynes, Marsh.
Scunthorpe: Slocombe, Ribeiro, Mirfin, Canavan, Nolan, Hawkridge, Syers, McAllister, Williams, Burton, Adelakun (Collins ht).
Unused subs: Iwelumo, Esajas, Severn, Waterfall, Sparrow, Wootton.
Referee: Andrew Madley (West Yorkshire).
Attendance: 6,009 (527 from Scunthorpe).