Newcastle United suffered a Boxing Day blow as a strong Sheffield Wednesday left St James's Park with a deserved victory.
Defender Glenn Loovens headed home the only goal of the game after 53 minutes to give the play-off contenders all three points.
It was a tough evening for Rafa Benitez's Newcastle side, who struggled to create anything in the absence of suspended midfielder Jonjo Shelvey.
The Owls' physical game frustrated Benitez and the home fans, but in truth the scoreline could have been greater had it not been for some superb saves by Karl Darlow.
Jack Colback made a timely return from an eye injury to replace the Shelvey in the centre of Newcastle's midfield, with Benitez making two further changes from the side which beat Burton Albion - Yoan Gouffran and Vurnon Anita replacing Christian Atsu and DeAndre Yedlin.
It was the visitors who settled quickest but United almost grabbed the lead in the 12th minute, Dwight Gayle rattling the angle of the woodwork after being fed by Mohamed Diame in the inside left position, with former Sunderland shot-stopper Kieren Westwood having got fingertips to the effort.
The visitors almost took the lead three times in a five minute period, however. First former Sunderland striker Steven Fletcher produced a great save from Darlow as he swivelled on a Daniel Pudil cross, and from the resulting corner Wednesday went close again from a scramble inside the box.
And Liam Palmer should have done better after out-witting and outpacing Paul Dummett, only to scoop his effort over the crossbar.
At the other end, Ciaren Clark headed wide from a Matt Ritchie corner when he should have done better, before the first half descended into a niggly affair with fouls on both sides.
After the break, it was Wednesday who started brighter and on 49 minutes, Darlow had to produce a stunning stop from point-blank range to deny Fletcher the opener.
Newcastle failed to heed the warning signs, however, and when Darlow performed heroics again to save Fletcher's header, Forestieri kept the ball alive and Owls skipper Loovens nodded home from the edge of the six-yard box to give Wednesday a 53rd-minute lead.
Gouffran put a diving header inches wide from Colback's cross but it was his replacement, Christian Atsu, who tested Westwood with a fierce effort from distance which the keeper tipped over.
And United's final substitute, Aleksandar Mitrovic, had a firm header from a corner comfortably saved by the Owls shot-stopper as United failed to extend their lead at the top of the Championship, a lead they could lose when Brighton play tomorrow.
NEWCASTLE UNITED: Darlow; Anita, Lascelles, Clark, Dummett; Hayden, Colback (Mitrovic 80); Ritchie, Diame (Perez 69), Gouffran (Atsu 63); Gayle. Subs: Sels, Yedlin, Lazaar, Mbemba, Mitrovic.
SHEFFIELD WEDNESDAY: Westwood, Palmer, Lees, Loovens, Pudil, Wallace (Nuhiu 90), Hutchinson, Bannan (Joao), Reach, Forestieri (Jones 80), Fletcher. Subs: Wildsmith, Abdi, Joao, Hunt, Sasso.