Two goals in the second half condemned Posh to defeat at Hillsborough.
Peterborough United suffered their first defeat in three as Sheffield Wednesday moved out of the relegation zone at Darren Ferguson's men expense with a hard fought 2-1 victory at Hillsborough.
Bobby Olejnik made the first save of the afternoon on six minutes as he prevented former Cardiff City man Jay Bothroyd from squeezing in a low shot at his near post after the striker had beaten the offside trap.
George Boyd tested Chris Kirkland at the other end, but his effort from 25-yards was weak and was comfortable for the experienced shot-stopper.
Miguel Llera saw a looping header go over the top on 13 minutes after the first corner kick from the hosts. Llera headed over again from another set-piece moments later as the Owls created the chances in the opening exchanges.
Barkley was booked for a late tackle on Nthle on 24 minutes, but the youngster helped the on-loan midfielder by bouncing straight back up.
Tomlin saw a shot blocked on 37 minutes after excellent approach play from Berahino before Bostwick blazed the rebound over from 35-yards.
The Owls broke the deadlock within 60 seconds of the second half as Ross BARKLEY got in behind the Posh defence and from a tight angle squeezed a shot past Bobby Olejnik, via the aid of a large deflection. A nightmare start to the second period.
Bostwick was booked for a trip on Barkley on 53 minutes as Darren Ferguson instructed some of his substitutes to warm up. Posh were dealt a blow on the hour mark as Ntlhe was stretchered off after a tackle by the touchline. Joe Newell replaced him at left-wing back.
Sheffield Wednesday wanted a penalty kick on 63 minutes as Antonio tussled with Brisley, but referee Darren Drysdale gave nothing. Berahino fired over from distance at the other end.
Bostwick fired wide via the aid of a deflection on 67 minutes, but the referee gave a goal-kick. Antonio squandered a great chance to make it 2-0 when he was sent clear, his shot going wide of the target from 10-yards.
It was 2-0 to the home side on 76 minutes as powerful defender LLERA headed home from close-range, a deserved second goal for the Owls on the strength of their second half display.
Posh reduced the arrears almost immediately as George BOYD fired home with his right-foot from 10-yards after good work from substitute Joe Newell. Nathaniel Mendez-Laing replaced the hard-working Berahino on 80 minutes.
Llera was denied comfortably by Olejnik on 85 minutes after good work from the pacy Antonio.
Final Score: Sheffield Wed 2-1 Posh
Sheff Wed: Kirkland, Buxton, Gardner, Semedo, Antonio, O'Grady (sub Madine 67min), Corry (sub McCabe 22min), Bothroyd (sub Johnson 88min), Barkley, Jones, Llera. Unused subs: Davies, Taylor, Mattock, Rodri.
Posh: Olejnik, Little, Alcock, Knight-Percival, Brisley, Ntlhe (sub Newell 60min), Boyd, Bostwick, McCann (sub Swanson 73min), Tomlin, Berahino (sub Mendez-Laing 80min). Unused subs: Day, Zakuani, Barnett, Ferdinand.