United and Hull battle it out for the chance to play Arsenal or reigning champions Wigan Athletic in the final - both looking to benefit from the earlier elimination of some of the competition's bigger clubs.
Despite being the lowest ranked team left in the draw, Deane is confident Nigel Clough's men can add another Premier League scalp to the likes of Aston Villa and Fulham, who were both dumped out by United earlier in the campaign.
Deane, who played at Bramall Lane for seven years over three spells, claims the fact United have no play-off commitments or relegation fears can aid them in the cup.
Asked by Perform whether United could spring a surprise at Wembley, he said: "Why not? I did an interview before the Fulham game and I said, 'why not?'
"This is no different a scenario. They've got nothing to lose and are playing off the back of a good stretch of form.
"It's an extra game - a bonus game. They're safe, so they'll go out there and I'm sure they'll give it their all.
"It's a fantastic club is Sheffield United and it's the typical rollercoaster journey."
Clough has overseen an impressive turnaround at Bramall Lane since taking over from David Weir in October.
While their play-off dream has faded, Clough has taken them to the verge of their first FA Cup final since 1936.
"I kind of feel a little bit sorry for David Weir because it's a bigger club than some people think it is," he added.
"It perhaps takes time when it's your first appointment as a manager - coming into a club that size, which really is a Premier League club.
"It's big enough to be a Premier League club and the expectation of the fans is always going to be high. Everyone who comes into a job that like that - you're seen as the messiah.
"But I think Nigel Clough has come in and he's got a wealth of experience. He's come in and done very well. Certainly, the fans are happy with how things have gone down there since he's come in."
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