Luke Daly struck in the fifth minute of injury-time to give South Shields a 3-2 win over Scarborough Athletic, who had chucked every man including their goalkeeper up for a late corner as they hunted for a win that they wrongly thought would keep them in the play-off chase.
That denied Farsley Celtic the title after they had beaten Whitby Town 2-0 with goals from Will Hayhurst and Nathan Cartman.
The Yorkshiremen are still heavy favourites, holding a three point lead going in to the final day, where they host Marine and South Shields travel to Gainsborough.
Gainsborough will need a result in that game to wrestle their play-off spot back off Buxton, who took charge of fifth place with a 6-0 thrashing of local rivals Matlock Town.
Liam Hardy scored four for the Bucks, who now boast a two goal cushion over the Holy Blues ahead of their game against Warrington Town on the final day.
Warrington are now out of the title race after a goalless draw against Witton Albion.
It was a stark contrast to 48 hours earlier when the Yellows’ win over Stalybridge, coupled with dropped points for Farsley and South Shields, meant they had moved within two points of the leaders.
But they will now be in the play-offs only, slipping to third in the table, and needing a result at Buxton as well as a Shields slip to get second and the potentially all important guarantee of a home semi-final and final.
The relegation battle will be decided on the final day too, with any one of three teams at risk.
Mickleover Sports sit in the danger zone currently on 38 points, after going down 1-0 at home to Basford United on Monday, a point adrift of a freefalling Stalybridge, who were beaten 1-0 at Hyde United.
Celtic have 39 points, a point behind Marine, who were 2-0 losers to Bamber Bridge on Monday.
Alistair Waddecar, joint top goalscorer in the league with James Walshaw, scored a brace to complete a remarkable revival for Brig who are now guaranteed to be plying their trade in the Premier Division next season.
Also safe are Grantham Town, despite going down 2-0 at home to Gainsborough Trinity, conceding goals a minute either side of half time.
Stafford Rangers also secured their survival with a 1-0 win at Nantwich Town, who are guaranteed to finish fourth in the league.
The only other two clubs guaranteed of their final position going in to the last game are Hyde, who are locked in 10th spot, and bottom placed Workington.
To view all the results from the weekend’s games, visit the EVO-STIK League results page, and check the latest league tables here.