Brighouse won 3-0 at Spalding United, while Colls drew 1-1 at Ossett United, who now can’t finish any higher than fourth.
Ossett and Sheffield currently hold the other two play-off spots, and they have a three point advantage over Tadcaster Albion, who stayed alive with a 90th minute equaliser by Aiden Savory in a 1-1 draw at Pickering Town.
Tadcaster need Sheffield to slip up on the final day, and then to win themselves, to sneak in on goal difference.
Ossett are virtually guaranteed a play-off spot, but for an unlikely goal difference swing.
Sheffield missed out on the chance to secure their spot as they were held to a goalless draw by Belper Town.
At the bottom, Gresley still have a chance to avoid the drop despite losing 2-1 at home to Loughborough Dynamo.
They are two points behind Carlton Town, themselves 2-0 losers at home to AFC Mansfield, who will take one of the two relegation spots having resigned from the league at the end of the season.
That means whoever finishes 19th will earn a reprieve, with Carlton currently on 27 points, ahead of Gresley on 25.
Champions Morpeth beat Marske United 3-1, while a Brody Robertson hat-trick fired Cleethorpes Town to a 4-1 win at Lincoln United.
Elsewhere, Frickley beat Stocksbridge Park Steels 2-0 and Stamford played out a goalless draw with Wisbech Town.
To view all the results from the weekend’s games, visit the EVO-STIK League results page, and check the latest league tables here.