Jack Robinson seemed to have sealed the points with a cool finish after John Egan had headed a corner back into his path, but Folarin Balogun pulled one back moments later after a slip from Blades keeper Wes Foderingham.

But Morgan Gibbs-White sealed United's victory with a superb fourth goal as he flicked home Ben Osborn's cross.

The win sees Sheffield United move above Middlesbrough into fifth place, with Wilder's side dropping into eighth, two points off the play-off places.

Wilder left United just under a year ago, after almost five years in charge - in which time he led the Blades from League One into the Premier League.

He had seen his new Boro side climb into the play-off places, a point above his former club, since taking over from Neil Warnock in November and they had an early penalty appeal waved away when Isaiah Jones went down under a challenge from Rhys Norrington-Davies.

Berge - one of Wilder's most expensive signings during his time at Bramall Lane - was influential throughout the opening period and the Norwegian was rewarded when Sharp raced on to a long throw down the left and his cross from the byeline was palmed into the midfielder's path by Joe Lumley.

United soon doubled their lead as Jonny Howson was dispossessed in midfield, allowing Gibbs-White to break into the penalty area and square a pass to Sharp for a simple finish.

The visitors should have got back into the game four minutes later, but Andraz Sporar blazed a shot over from six yards after good work by Jones. United could have been out of sight 10 minutes before the break had Lumley not saved with his legs after Gibbs-White broke clear.

Aaron Connolly thought he had cut the deficit early in the second half but his neat finish was ruled out for offside after a nice cross from Thomas, while Berge fired a low effort just wide for the Blades soon after.

Robinson seemed to have calmed any nerves as he volleyed in the third goal from inside the six-yard box, only for on-loan Arsenal man Balogun to slot his first Boro goal into an empty net when United keeper Foderingham slipped as he went to clear.

Duncan Watmore had a shot blocked soon after as Boro threw three men up front, while Connolly curled an effort just wide. Gibbs-White ended any lingering doubts, though, as he acrobatically flicked Osborn's cross underneath his body and into the far corner.

Sheffield United boss Paul Heckingbottom told BBC Radio Sheffield:

"I thought we were good from the first minute to the last. Much as we try you can't have days like that every day.

"We made some changes to how we wanted to play based on Friday's game and based on Boro. I've praised everyone in the changing room because there's lots of things we spoke about that we executed really well.

"It was a good goal from Morgan. It was audacious or cheeky if you like but you back him to do it. He performed his role for the team tonight.

"Maybe it sends out a message but it's the same again on Saturday in terms of teams in the top half playing against one another."

Middlesbrough boss Chris Wilder told BBC Radio Tees:

"It was a little bit more than painful. It was a really poor performance from us.

"It wasn't a tactical battle, they just out-performed us individually. There are no positives for us tonight.

"I'm quite shocked how poor the players were, there's no hiding place. I've got no complaints about the result.

"I thought we'd trained really well and I got a good vibe from the players before the game. I didn't expect us to play in that manner. It's a real eye-opener."