Kilsyth Rangers suffered only their second defeat of the season as they went down 3-0 to Clydebank at Duncansfield on Saturday.
Despite the loss, and almost certainly their poorest performance of the campaign, they remained top of the table - but it was the result Clydebank needed to blow the promotion race wide open with the top seven sides now separated by just five points.
Clydebank set out their intentions straight away and after only eight minutes they won a penalty when Chris Reid, probably accidentally, handled the ball when Mark Burbidge made a good run into the box. Nicky Little put the spot-kick behind Andy Carlin.
Things went from bad to worse for Rangers just a little later when indecision between David Waters and Carlin let Burbidge lob the ball over both into an empty net.
Mark Tyrrell hit a free-kick over for Kilsyth, but Clydebank were clearly the better side going forward with Burbidge a constant threat.
It was just after the half-hour mark before Rangers got a decent shot on target, Scott Upton hitting a fine drive from 30 yards, but Clydebank keeper Josh Lumsden was up to the task and diverted the ball over for a corner kick.
At the other end, almost on half-time, Jordan Shelvey was clean through on Carlin but his finish was weak.
Rangers had a brief flurry of pressure early in the second half with Paul McBride skimming the crossbar with a good effort from about 18 yards.
Nicky Prentice then got in a decent shot under pressure, but again Lumsden made a good save.
However less than 10 minutes into the second period the game was effectively ended as a contest when Little broke through, with little opposition, and had an easy task to slot the ball past Carlin.
Thereafter the heat went out of the game, Clydebank simply had to hold on to what they had and did so easily.
Rangers made changes with Ian Diack on for Gary Livingstone, then Franny Kelly replacing Gary Kelly, but it made no discernible difference to the pattern of play on a bad day for Rangers.