A stunning double from Guylain Ndumbu-Nsungu revived Wednesday's fading play-off hopes and edged Barnsley further away after a 2-1 win at Hillsborough.
The Congolese star took his season's tally to ten as new Barnsley boss Paul Hart suffered his first defeat since taking over.
It stretches Barnsley's dismal run to just one win in 15 matches after they led the table early in the season.
Ndumbu-Nsungu grabbed his first in 36 minutes and added his second ten minutes into the second half before Robbie Williams pulled one back from the penalty spot.
Wednesday had Kevin Pressman to thank for two outstanding early saves as Barnsley threatened to take the lead.
The veteran Hillsborough keeper did well to cut out a stunning ninth-minute volley from Alex Neil following a cross from Kevin Betsy.
Pressman caused panic when he fumbled a testing cross from Neil Austin he recovered to keep the visitors at bay.
Pressman was at his best again in the 20th minute when Betsy's threaded pass brought a shot from Boulding.
Barnsley produced a crisp, slick move to open up Wednesday in the 33rd minute but after a low cross from Michael Boulding, Daniel Nardiello's shot was blocked at point blank range by Pressman and Betsy smashed over the follow-up.
Wednesday pounced immediately and seized the initiative. A long throw from Leigh Bromby was headed on by Kim Olsen and Ndumbu-Nsungu was the first to react and smash in a close range shot to claim the lead.
And when Barnsley dithered in the 55th minute Ndumbu-Nsungu robbed David Murphy and smashed his shot past Marlon Beresford.
He could have had a hat trick soon afterwards but blazed his shot wide and was then denied by a Beresford save.
Teenager Williams crashed in his first senior goal for Barnsley from the spot after Antony Kay was bundled over in the box. It sparked a high energy finish but Wednesday held on to claim the points.