Leaders Tadcaster Albion gave their supporters a night to forget after a shock 3-0 defeat to Cleethorpes Town at i2i Sports Stadium.
Alongside a poor performance, Tadcaster failed to score in a Toolstation NCEL Premier Division game for the first time this season.
Three goals in four second half minutes killed Tadcaster off, but the writing had been on the wall for some time.
Tadcaster will still be top at Christmas, but if second-placed Shaw Lane Aquaforce win their two games in hand, Craig Elliott’s men will be one point behind them.
The resounding away win was also a huge marker for newly-promoted Cleethorpes, whose manager Marcus Newell described the victory as his club’s greatest win so far in their short history.
For whatever reason, Tadcaster served up their worst display of an almost perfect campaign.
Paul Marshall’s side were sluggish going forward and for a team that had prided itself on its ability to keep possession of the ball – all that went out of the window.
Tadcaster struggled to string passes together and Cleethorpes looked dangerous on the front foot.
Even in the first half, Cleethorpes were the most likely to score first as Pete Lawrie needed to make two saves from Darren Hanslip and then Marc Cooper.
Tadcaster changed their system around for the second half with right-back George Bissett moving into a attacking position.
The alterations initially appeared to have worked a treat. Bissett’s neat overlap allowed captain Nick Thompson to strike at goal from the edge of the penalty area.
Tadcaster fans had their arms in the air as the shot flew towards goalkeeper Brad Beattie. Unfortunately the ball struck the advertising boards instead of the net.
However, Tadcaster failed to retain the intensity as Cleethorpes mounted an enormous amount of pressure.
Two big let-offs quickly followed as Brody Robertson raced through and lobbed Lawrie – only for the roof of the net to save Tadcaster.
Lawrie then proved to be alert as Cooper did the same, but pulled a good save out of the advancing goalkeeper.
But, Lawrie, playing because of Tom Morgan’s rib injury, wasn’t going to keep the visitors out forever and the bough soon broke.
Louis Grant broke away and scored with a low finish from distance as Lawrie tried his best to narrow the angle.
Conceding one goal wasn’t such a problem at first for Tadcaster with 20 minutes.
Marshall and his side have dug themselves out of tighter spots in recent memory, but that kind of luck ran out last night.
The Taddy boss was ready to bring on the calvary with Calum Ward and David Brown ready to make an entrance, but it was too late by the time they arrived.
Tadcaster’s night was summed up just 90 seconds later when Denny Ingram’s wayward back-pass deceived Lawrie and trickled over the goal-line.
Lawrie then made a excellent save from a header in the six-yard-box, but Taddy defenders failed to react and Cooper was able to score his deserved goal.
That removed any hopes of a comeback and the game petered out.