SHEFFIELD UNITED manager Paul Heckingbottom says that the anger which led to his dismissal in the 76th minute of his side's 3-1 home loss to promotion rivals Middlesbrough represented a build-up of frustration at a host of decisions coming against his side previously this term.

A bad night at the office was compounded when the Blades chief was sent to the stands after what he believed to be a foul ahead of the visitors' killer third strike - a second goal for Cameron Archer.

Heckingbottom felt that play should have stopped after James McAtee appeared to be impeded by Hayden Hackney, despite staying on his feet with the Boro midfielder setting up Archer for the goal. The advantage did not favour United.

He sarcastically applauded referee Andre Marriner before being dismissed and also lashed out at the fourth-official sign.

Heckingbottom, whose side's lead over third-placed Boro was cut to seven points, although the Blades do have a game in hand, said: "It's nothing to do with this game, my frustration has been building over the season.

"We are an honest team but in our conversations about McAtee and (Sander) Berge getting fouled, we get double punishments because we don't get bookings and we're not getting free-kicks.

"I'm having conversations with my assistants about whether we should go down.

"I shouldn't react that way but it's not that game.

"We're getting punished, I think, for our honesty. As football, we're rewarding people for going down."

On his side's performance, which saw them take the lead early on through Oli McBurnie, but failed to convert more chances ahead of Boro getting their act together in impressive fashion, he added: "It was a good first half, both teams would have probably said a draw would have been fine.

"Their big moments came when we didn't get the press right.

"They get a break at the start of the second half and we responded well. We weren't at our best, but we had chances.

"We know we weren't at our best but we still had more than enough efforts on target to get something out of the game.

"You just continue what we've been doing. it's still a big gap, we've still got the game in hand and lots of games to play. If we're at our best, we're fine. We weren't today."

Paul Heckingbottom opens up on his dismissal in Sheffield United's loss to Championship rivals Middlesbrough FC