Missed chances after a lack-lustre first-half performance meant 10-men Belper Town went down 3-1 at home to inform Tadcaster Albion.
The visitors, unbeaten in five matches, had arrived at Belper only ahead of the Nailers on goal difference.
But they pulled three points clear of the home side in the race for a play-off place in the Northern Premier League Division One East.
Tadcaster built up a three-goal lead before Piteu Crouz replied from the penalty-spot. Substitute Jake Sturgess, who received two yellow cards, was then dismissed as Belper slipped to eighth.
Belper’s backline was under the cosh in the opening exchanges and their resistance was tested by a physically imposing opposition.
Prolific marksman Joe Lumsden looked to catch out home keeper Leigh Overton out with a clever flicked header, which the Belper keeper acrobatically tipped over.
But the Nailers paid the price for committing fouls when Billy Whitehouse broke the deadlock from a free kick.
As the fouls mounted up Craig Nelthorpe was deemed to have tripped Whitehouse inside the area.
After a discussion with his officials the referee changed his decision to a free kick on the edge of the area, but Patrick Miller converted the set-piece to make it 2-0.
Grant Black’s side improved after the break, led by three half-time substitutions.
Substitute Kai Hancock, who had earned the matchball in midweek, three times went close as Tadcaster rode their luck.
But searching for a comeback meant Belper were vulnerable to the counter-attack and Peter Davidson drifted past attempted challenges to the byline and pulled the ball back for Lumsden to score.
Alex Peterson was felled in the box following a late challenge to give Crouz the chance to redeem some Belper pride from a promising second half performance and Danny Gordon was unfortunate to see his header hit the bar.
Belper Town: Overton, Lucas, Clark, Gordon, Peterson, Assenso, Nelthorpe (Paylor 45), Robson, Curtis (Hancock 45), Milner (Sturgess 45), Crouz. Unused subs: Esmaiely, Hough.
Tadcaster Albion: Ingham, Barkworth (Barrett 88), Walters, Rose (Roper 86), Coates, Miller, Whitehouse (Stewart 75), Davidson, Lumsden, Howarth, Savory. Unused subs: Mycoe, Hardy.
Ref: Gareth Thomas.