Wednesday dominated for long periods but were caught out with goals from strike duo Neil Mellor and Jon Parkin with luck firmly on their side, as both goals took deflections on their way past keeper Lee Grant.
Preston survived two early scares as Wednesday looked for an early breakthrough, Michael Gray's teasing corner finding Jermaine Johnson whose downward header at the far post beat beat Andy Lonergan only for the ball to flash the wrong side of the woodwork.
The Lancashire side were in trouble again minutes later when they failed to cut out Tommy Spurr's cross from the left. Leon Clarke connected six yards out as the Preston keeper pulled off a spectacular stop; tipping the ball round the post.
Wednesday almost fell behind when Ross Wallace was given too much space on the left flank and centre-back Mark Beevers miscued as he tried to clear to see the ball spin inches over the bar.
Preston snatched the lead on 20 minutes, when Eddie Nolan's cross was met by Mellor, whose close range strike shaved the chest of centre-back Darren Purse on its way over the line.
Wednesday were back on level terms in the 38th minute with a stunning goal, Gray's perfectly flighted free kick finding the top right hand corner of the net with Lonergan helpless.
Preston, content to hit Wednesday on the break, were handed a half chance when Mellor was given space to lash in a low drive which was smothered by the diving Grant. Purse almost grabbed a second for Wednesday in first half stoppage time, but his close range header deflected onto the woodwork.
In the 55th minute, Mellor picking out Parkin who finished with a low strike from 15 yards which took a cruel deflection as it wrong-footed Grant.
Midfielder James O'Connor went close on 71 minutes, as his far post header from Lewis Buxton's cross flew a fraction over the target before Liam Chilvers cleared a Johnson effort off the line in the dying minutes.