OXFORD United’s promotion challenge stuttered as defensive mistakes saw them slip to a costly defeat at home to Luton Town.

Danny Hylton put them in front early on, but out of nowhere Luton were allowed two goals in three minutes right at the end of the first half.

Chey Dunkley levelled shortly after the restart, only for another defensive lapse to allow Joe Pigott to score his second goal of the game.

James Roberts came closest to salvaging a point when his shot was turned on to the post in the closing stages, but United came up short.

With Bristol Rovers winning, their advantage over fourth place was slashed to a point with four games remaining.

Illness ruled out wingers Callum O’Dowda and Alex MacDonald, so Kemar Roofe and George Waring were promoted to the starting line-up.

The final change for the home side saw John Lundstram, back from suspension, come in for Josh Ruffels, who was still struggling with a shin injury.

United’s home form has not been good, but they got away to a perfect start.

Less than two minutes were on the clock when Roofe slipped in Hylton, who took a touch before picking out the far corner of the net.

It was just the nerve-settler head coach Michael Appleton would have hoped for beforehand and his side went on to move the ball with purpose.

Luton had to defend well to keep United out, although Elliot Justham was not tested again before the break.

The visitors needed a win to keep their faint hopes of gatecrashing the play-offs alive.

They battled to stay in the game and it took an excellent block from Lundstram to keep out a sweet strike from Lee midway through the half.

United looked in control of the game, though, and Chris Maguire came within inches of doubling the lead with a dangerous free-kick late in the half.

That would have put the hosts well on the way to three precious points, but instead somehow they went in at the break behind.

A torrid three minutes began when Jonjoe Kenny played a bouncing pass back to Buchel, who took a bad first touch and the goalkeeper slipped as he went to clear.

The ball sliced for Josh McQuoid, who squared to give Pigott a simple finish.

It was a huge blow for United, who still appeared to be reeling in stoppage time.

A hurried clearance from Johnny Mullins felt to Danny Green, whose cross found an unmarked Lee to slam in on the volley from ten yards.

A shell-shocked crowd at the Kassam Stadium could not believe what they had just witnessed, so there was a roar of relief when United drew level six minutes after the restart.

Hylton was fouled out wide and from Maguire’s delivery Dunkley headed the ball down and into the far corner.

United briefly had their tails up and might have landed another blow, but Waring’s pass for Roofe was heavy and allowed Justham to gather.

But the momentum quickly faded, as more dreadful defending saw Pigott pounce again just before the hour mark.

Luton were given room to play and when Ruddock Mpanzu flicked a high ball into the box the striker got in between Kenny and Mullins to control the ball and pick his spot from ten yards.

It left United with it all to do again.

Jordan Bowery was brought on and when that failed to have the desired impact James Roberts followed from the bench.

Within five minutes the teenager, making his first appearance at the Kassam Stadium for a year, came so close to an equaliser.

When the ball came his way in the box the striker smashed a first-time shot which took a brilliant save from Justham to turn on to his left-hand post and rebound clear.

United continued to push late on, but Hylton and Sercombe could not keep efforts down as Luton hung on for the victory.

Oxford United: Buchel, Kenny, Mullins, Dunkley, Evans, Roofe, Sercombe, Lundstram, Maguire (Roberts 76), Hylton, Waring (Bowery 61).

Unused subs: Slocombe, Wright, Ruffels, Ashby, Giles.

Luton Tn: Justham, O’Donnell, Potts, Sheehan, Rea, Lawless, Lee (McGeehan 70), Ruddock Mpanzu, Green, McQuoid (Howells 90), Pigott.

Unused subs: King, Benson, Marriott, Banton, Musonda.

Referee: Trevor Kettle (Leicestershire).

Attendance: 8,838 (816 visitors).