Siriki Dembele’s first-half goal gave struggling Oxford a 1-0 win over promotion-chasing Sheffield United at the Kassam Stadium and ruined Chris Wilder’s return to his former club.

It denied the Blades a return to the top of the Sky Bet Championship table,  where they had started the day.

Burnley’s 2-1 victory at Coventry had earlier taken the Charets to the top – and Wilder’s team could do nothing about it.

In a scrappy encounter, Dembele struck in the 38th minute, rolling the ball past goalkeeper Michael Cooper from close range after Michal Helik then Ciaron Brown helped on Will Vaulks’ long throw.

It was only Dembele’s second goal of the season – he also hit the winner in Oxford’s previous home game against Watford.

The Blades, who had boasted the best away record in the Championship, were not at their best but came up against an Oxford side that battled for everything in difficult, windy conditions.

Oxford boss Gary Rowett reverted to the side that beat Watford 1-0 in their last home fixture, while Wilder named an unchanged side.

After a quiet start, Rhian Brewster fired in a shot on the turn that took a slight deflection for the visitors. Soon after, at the other end, Oxford centre-half Helik met Dembele’s corner with a firm header which was straight at goalkeeper Michael Cooper.

Oxford’s players were adamant that forward Ole Romeny was elbowed when he went for a header inside the box but neither referee James Linington nor his assistant saw it.

Wilder’s men went close in the 22nd minute when Harrison Burrows took a return pass to get in behind the home defence and struck an early angled shot that Jamie Cumming beat away.

Cumming made an even better save with an outstretched leg from Tyrese Campbell’s low shot.

Oxford relied a lot on Vaulks’ long throws and the height of Helik, Brown and Ben Nelson.

There was a good response from the Blades after going behind, with Cumming having to make a smart save from Sydie Peck at his near post.

The visitors piled on the pressure in the second half, with Oxford hoping to capitalise on quick counter-attacks.

Brown made an outstanding last-ditch interception when Brewster threatened, before Cumming got down low to save an unconvincing Campbell effort.

Peck tried his luck from 30 yards and saw the shot whistle past the post.

Oxford defended frantically at times, both from corners and Jack Robinson’s long throws, but held out for only their second win in 12 games – and a massive three points in their bid to beat the drop.