The Owls Under-21s suffered their first defeat of the campaign on Monday evening at the Cardiff City Stadium.
The Bluebirds were 3-0 winners on the night with goals from Theo Wharton (2) and Rhys Healey all coming in eight second half minutes.
Wednesday started brightly as Matt Penney tested Luke O’Reilly in the Cardiff goal, who held on to the strike.
But the hosts came back with Kadeem Harris, whose powerful shot was superbly blocked by Will De Havilland and Matt Kennedy, who brought a fine save from Brad McDonagh.
Cardiff finished the half with a flourish with Jamie Veale hitting over from outside the area before Harris fired wide on the stroke of half time.
Wednesday made a positive start after the break and Warren Clarke went close with a half volley but the hosts ran away with the game inside eight second half minutes.
First Wharton headed past McDonagh from a flag kick on 68 minutes and scored a second moments later, burying low into the bottom corner from a give and go with Tommy O’Sullivan.
Healey then scored on the rebound after McDonagh had saved from O’Sullivan to seal the win and ensure no way back for Wednesday.
Owls: McDonagh, Booker, Wildin (Centano, 68), Edge (Clarke, 45), De Havilland, Beatson, Stobbs, Wright (Brown, 77), Hirst, Meadows, Penney.