Warrington suffered their first defeat in six games as Bradford claimed a much needed win.
Steve McNamara’s men fought hard for the points in what was ultimately a surprise victory considering Warrington’s form in recent weeks.
Deacon slotted over a drop goal on the hooter to make it 9-0 at the break, emphasising just how tight the game was.
But Terry Newton put the game beyond doubt in the final quarter, Deacon’s conversion putting them 21-6 to the good.
Despite a late effort from Chris Hicks, the Warrington fans went home unhappy after missing their chance to climb in to the top eight.