Sheffield United returned to the top of the Championship in a hard-fought 1-0 victory as Neil Harris’ penultimate match in charge of Millwall ended in defeat.

Harris returned to The Den as manager in February, over four years after resigning from the role, but the club announced on Tuesday that a “mutual decision” had been taken for the former striker to leave after the game at Middlesbrough on Saturday.

League leaders United had shown signs of their best in the first half, with Rhian Brewster rounding off a fine move in the 42nd minute to help Chris Wilder’s men climb above Leeds.

A second successive loss for Millwall after Saturday’s defeat to Coventry marked their fifth match without a win as the south Londoners strayed further away from the play-off positions.

Sheffield United showed the exact quality in the early exchanges as to why they find themselves in a promotion battle.

After some quality footwork by Gustavo Hamer in the eighth minute, Harrison Burrows’ drilled effort from the edge of the area took an awkward deflection and bobbled behind for a corner, much to the relief of well-beaten goalkeeper Lukas Jensen.

The Blades showcased an attractive brand of football and neat one-touch passes through the lines by the likes of Hamer and Callum O’Hare eventually saw the ball fall to Chelsea loanee Alfie Gilchrist, who overlapped down the right-hand side of the box, but the right-back failed to squeeze his effort in from an acute angle.

Millwall rode the storm and threw men forward in a bid to land the first blow midway through the half.

After Duncan Watmore was denied by some good defending to get a shot off in a one-versus-one situation, Japhet Tanganga cut in and shot from the subsequent move, but his effort cannoned off the outside of the left post and out of play.

The hosts’ new-found momentum was soon disrupted when United put together a clinical move to earn the lead going into half-time.

A perfectly weighted pass over the top to the surging Hamer down the right saw the midfielder cut a ball across the six-yard box to the well-positioned Brewster to tap home.

Wilder’s side made their intentions clear after interval, with the visitors dominating the ball in a bid to stifle play.

While the Blades displayed greater quality than their opponents, while it remained 1-0 Millwall were very much in the match, but a lack of midfield control saw spells of possession short-lived as the contest started to ebb away.

Appeals for a penalty after a challenge on Romain Esse inside the area were waved away by referee Matthew Donohue in the 85th minute as Millwall enjoyed a late flurry of chances, but United survived.