Chorley will go to Buxton on Saturday sitting on top of the Evo-Stik League and knowing a win will seal the title.
For most of yesterday afternoon, it looked as the Magpies would be crowned champions.
But second-placed FC United fought back from two goals down to win 3-2 against Ashton United to take the title to the final game of the season.
In the Victory Park sunshine, first-half goals from James Dean and Darren Stephenson had given Chorley a 2-0 lead at the break, and second-half strikes from Dean and Chris Almond sealed the three points.
Magpies boss Garry Flitcroft said: “With FC United scoring in the final minutes, that’s how it goes.
“We have played well today and scored four great goals so it means going to Buxton and having to win the title there.
“It’s disappointing that the result hasn’t gone for us but we will go into Saturday looking forward to it.
“Buxton have lost eight games at home this season which is a lot of games to be losing, so it shows their home form isn’t great.
“We’ve just got to make sure we get the right result.
“ I know my lads will be up for it as they’ve worked so hard for where we need to be.
“The fans can be huge for us – it will be massive.
“The atmosphere today was excellent and we want to take those singers up to Buxton with us to cheer us on.”
There was almost a perfect start for Chorley against Marine as Dale Whitham scuffed a shot at goal which found its way to Josh Hine, but his shot was deflected for a corner.
Marine’s Andy Fowler was then denied by an excellent Keil O’Brien sliding challenge after the tricky winger got in behind the centre-half.
The Magpies then took lead after 17 minutes.
Whitham whipped in a free-kick at pace which goalkeeper Callum Williams could only fumble and on hand was Dean, who from six-yards slotted an effort into the bottom corner.
And the Victory Park faithful was sent wild once again
after 26 minutes. Dean saw his shot blocked but from the rebound, he pulled the ball back across goal and on hand was Stephenson ,who lifted the ball into the roof of the net.
Chorley continued to attack Marine but the visitors looked dangerous on the break, with Josh Sumner twice getting in behind the Chorley back-line.
Roared on by an excellent crowd of 2,128, Chorley had another effort on goal but Stephenson’s effort with his back to goal was comfortably saved by Williams.
The Magpies added a third three minutes after the
Hine pounced on a loose ball down the right-hand side and after a moment of trickery, he whipped in a pinpoint cross for Dean who headed the ball into the top corner.
Chorley goalkeeper Sam Ashton was called into action soon after when a ball was curled into the box and Marine target man Will Jones headed at goal but Ashton made a smart block with his chest.
Dean, could have grabbed his hat-trick just after the hour mark but he failed to connect properly with an Alex Nicholson cross, skewing his effort wide.
The game turned scrappy with Chorley seemingly happy to sit on their lead but as in the first half, Marine looked dangerous on the break.
Dale Wright stung the palms of Ashton with a curling free-kick while at the other end, Stephenson fired a tame effort straight at Williams. Fowler then forced Ashton into a save at his near post before the Chorley stopper was called into action once again, saving to his right from a Sumner free-kick.
With just two minutes left, Chorley added a fourth when substitute Chris Almond picked up on a loose ball and from 25 yards struck an effort low into the corner.
Chorley : Ashton, Nicholson (Ross 70) , Cottrell, Teague, O’Brien, Roscoe (Almond 56), Hine, Stephenson, Dean, Whitham, Jarvis. Subs: Anderton, Zibaka, Grundy (gk)