There were a few early chances on the rain-soaked pitch with the appropriately-named James Spray forcing a save out of Sam Johnstone after being put through by Nathaniel Mendez-Laing. John Gorman, who was at United as a kid, headed just wide as Wolves continued to threaten before a move of real quality at the other end.
Marnick Vermijl powered forward to link well with Cole and the England Under-19 international's exquisite backheel allowed the Belgian to cut inside and curl a drive inches off target. First-teamer Stephen Hunt shanked one opening and Johnstone punched an Anthony Forde corner behind his own goal as the champions only showed flashes of their true quality, with Matty James forcing a decent stop out of Aaron McCarey following some persistent play by Vermijl.
Just when the first half appeared to be ending goalless, Ryan Tunnicliffe burst into the box to unselfishly feed Will Keane but the striker's close-range finish came back off a post when a goal seemed certain. Thankfully, Petrucci was lurking to blast into the unguarded net with real conviction.
Petrucci almost add a second moments after the restart when his effort was kept out by McCarey and Vermijl soon flashed an attempt wide from the edge of the box as United began the second half at a high tempo. The visitors responded with Forde testing Johnstone's reflexes but there was a scare for his opposite number when McCarey mishandled the greasy ball from a Petrucci cross but survived any real embarrassment.