Chris Wilder enjoying Sheffield United being hard to second-guess in Championship play-off final

This season has seen Wilder, who made his name playing an innovative 3-5-2 formation in his first spell at Bramall Lane, adopt a 4-2-3-1 formation.

Although the principles have stayed the same, in four of the last five matches he has gone to a 4-4-2 shape, allowing Kieffer Moore to have a partner alongside him at centre-forward to feed off the flick-ons when the Blades go direct more often.

How he thinks Sunderland will handle that approach, as opposed to Tyrese Campbell running the channels onto through-balls threaded by playmakers, will go a long way to deciding which formation Wilder adopts when the sides meet at Wembley on May 24, with a place in next season's Premier League at stake.

Adding to the uncertainty has been the quality of Callum O'Hare's performances from the bench in recent weeks. O'Hare scored in both legs of the Bristol City semi-final when Wilder changed formation to go with one out-and-out striker and the former Coventry City player operating in the hole behind him.

Ben Brereton Diaz missed the last four matches as he struggled with a virus, but is an option as a goalscoring wide attacker, particularly useful if the Blades opt for a lone centre-forward who could otherwise be isolated. The Chile international is expected to be fit at Wembley.

Add in the return of the club's only real out-and-out winger Jesurun Rak-Sakyi, plus two goals in four games from midfielder Andre Brooks, one of his rivals for a spot on the right, and it makes the Blades hard to second-guess.

"I've always said we're not a one-trick pony," insisted Wilder, whose side finished 10 points ahead of the Black Cats during the regular season. "We don't stick to one formation and keep that right the way through.

"We've changed shapes, we have to coach different shapes through the season.

"We've changed shapes to go for it, to see games out, to play against different styles and different opponents.

"We're going to have to try to get it as right as possible but always the most difficult job is for the players in terms of executing that gameplan.

"If we have to go over, we have to go round or through, we'll find the right way that gives us that best opportunity."

April saw the Blades fall out of a fiercely-contested title race with eventual winners Leeds United and Burnley, also promoted to next season's top flight. Wilder does not think that or his club's terrible record at Wembley and in play-offs will have any effect on his players.

"I don't feel there's a negativity because of our previous campaigns. There feels like a freshness about it, a real belief that we can make history and put to bed all the other things that have gone on previously."

The Blades have lost eight promotion play-offs as well as a relegation one under the previous format during Wilder’s playing days. They won their first game at Wembley, 100 years ago, but have lost all seven matches there since.