The Owls’ Under-18s suffered a cruel defeat across South Yorkshire at Barnsley.
Going down by the odd goal in five, Wednesday turned in a promising performance but were undone right at the last by a Reds penalty that took the spoils.
The Owls took charge early in a pulsating clash and created a raft of chances to take the lead, with George Hirst, Joe West and Fraser Preston each going close before the break.
But Barnsley took the lead moments after the restart when Sam Tingle fired a fine solo goal.
The visitors, though, promptly hit back to turn the derby game on its head.
First Jordan Lonchar drilled a low effort home from 20 yards before Hirst teed up nicely for Fraser Preston to slot the Owls into the lead.
Liam Waldock came within a whisker of making it 3-1 but the hosts levelled with ten minutes to go as Adam Lund executed a superb far post volley with some aplomb.
With the game heading for a stalemate, there was a sting in the tail and it fell in the favour of the Reds.
West was adjudged to have tripped Louis Wardle in the box and the latter stepped up to smash the resulting penalty into the back of the net.
Wednesday: Wallis, Hughes, West, Kirby, Lee, Brennan, Lonchar, Waldock (Swaine 81), Hirst, Hunt (Cook 73), Preston