Sheffield United: Wilder tells potential players they must '˜sacrifice' themselves for Blades

And, refusing to apologise for his hardline approach, Wilder insisted the outcome of last season’s promotion race proves temperament is the most important quality in League One.

“Character and attitude shouldn’t be behind ability,” he said.

“Being honest, they should be in front.

“Physically, it’s a tough competition. It’s 46 games over nine months, different conditions, weather and through ups and downs.

“Just as big, if not bigger, is the mentality of the player. He has to stick his lot in and be prepared to sacrifice himself for a team and club ethic.

“I don’t see that changing at any level really. You look at the top leagues and most successful teams of the last ten years.

“Look at Manchester United, Chelsea and the teams who have done well in the four divisons this year.”

“Look at the teams who got out of this division,” Wilder added.

“Burton and Wigan had good technical and technical players, but their mentality was really good.

“Burnley have been fantastic this year without the biggest budget, but mentally they were really strong.”

Wilder took charge of United last month after leading Northampton Town to the League Two title.

A new centre-half is now top of his wanted list after midfielder Mark Duffy and defender Chris Hussey arrived at Bramall Lane five days ago.

“The team who surprised everybody, Leicester, had some special stand-out qualities such as the togetherness and atittude of their players,” Wilder said.

“We will base it on all four things and they can’t have one without the other.

“Mentality of players is enormous and massive throughout the season.

“There’s four different parts of being a really good player.

“Technically, we want them to be good players who pass the ball and make good decisions.

“Tactically, we want them to do that and be adaptable and versatile.”

Meanwhile, Portsmouth fear they could be forced to fend-off interest from United as they attempt to lure Lee Novak to Fratton Park. The centre-forward spent last season on loan at Chesterfield.