Barnsley FC 0 Wycombe Wanderers 3: Reds undone by special strikes on sobering afternoon
The Reds went into the game on a high after making light work of Bristol Rovers at Oakwell in midweek but they found themselves on the wrong end of a 3-0 defeat on Saturday afternoon.
Wycombe, with Barnsley old boys Alfie Mawson and Josh Scowen in their ranks, showed superior quality in key moments.
Gareth Ainsworth's side were clinical in front of goal thanks to three special strikes from Anis Mehmeti, Dominic Gape and Nick Freeman.
Despite showing signs of a Wembley hangover in the opening weeks of the new campaign, Wycombe represented Barnsley's toughest examination since dropping out of the Championship.
For a side that had won their previous two home games without conceding, it was a shock to the system.
Fresh from their encouraging midweek victory, Barnsley edged a cagey opening and went close eight minutes in when Robbie Cundy saw a header well tipped over by Wycombe new boy Max Stryjek.
Garath McCleary blazed over from a tight angle at the other end as the visitors fired a warning shot of their own, but it was a slow burner of a game.
Barnsley did most of the running in the first half without carving out any clear-cut opportunities.
Liam Kitching tried to lift the tempo when he drove through the heart of the Wycombe midfield, only to see his 25-yard effort blocked.
Luca Connell shot straight at Stryjek from range and then headed over the bar as the Reds turned the screw.
But they were hit by a sucker punch on the break after switching off on 37 minutes.
It was Wycombe's first shot on target and Mehmeti made it count in some style.
Barnsley's response was immediate, Stryjek tipping over Jack Aitchison's rasping drive before punching the ball away from danger following a scramble in the box.
The Chairboys carried a threat on the break and carved out another opportunity for Mehmeti but, with three sides of Oakwell holding its breath, the striker shot straight at Collins.
One crisp counter-attack aside, long balls over the top were the biggest source of danger to leave Barnsley boss Duff with work to do at the break.
But Duff could only watch on as Wycombe took the game by the scruff of the neck after the interval.
Ainsworth's men should have doubled their lead just five minutes into the second period as Barnsley's goal led a charmed life.
McCleary worked an opening thanks to silky footwork but his effort came back off the post and Mehmeti was unable to turn the ball in on the line.
While Barnsley failed to create any meaningful chances, in the end Wycombe were indebted to moments of individual brilliance.
Gape scored the pick of the bunch, lobbing Collins from just outside the centre circle after spotting the Barnsley keeper off his line.
Matty Wolfe headed straight at Stryjek from Josh Benson's cross and substitute James Norwood saw a powerful strike deflected over as the Reds tried in vain to mount a response.
Freeman rounded off a miserable afternoon for the home side when he found the net with a superb 25-yard effort.
Barnsley: Collins, Andersen, Cundy, Kitching, Williams, Benson, Connell (Wolfe 59), Styles (Hondermarck 77), Thomas, Cole, Aitchison (Norwood 59). Substitutes unused: Walton, Cadden, McCarthy, Marsh.
Wycombe: Stryjek, Grimmer, Gape, Forino, Wheeler (McCarthy 85), Wing, Mehmeti (Freeman 71), McCleary (Al-Hamadi 82), Mawson, Obita, Scowen. Substitutes unused: Dickinson, Jacobson, Horgan, Pattenden.
Referee: O Yates.
Attendance: 9,978 (283 Wycombe fans).