Goals in the final few minutes of the game earned the Magpies a deserved three points when none looked likely.
Trailing to a 23rd minutes Liam Hearn goal, Chorley toiled and laboured but struggled to find a way through a resolute and packed Alfreton backline, but two goals created by Paul Jarvis and converted by Jack Sampson and Josh O’Keefe snatched victory from the jaws of defeat.
After a bright opening where Matt Challoner, Dale Whitham, Adam Blakeman and Andy Teague all had chance the first half settled in to dour encounter with the cold, wet and heavy conditions dominating both teams.
On 23 minutes Alfreton took the lead with their first attack. Paul Marshall and Andrew Monkhouse combined to slide in Hearn who kept his cool to finish from close range.
After the goal, Chorley pressed for an equaliser, but the visitors defended deep and in number, limiting space for the Chorley attack.
Jarvis volleyed straight into Fabian Spiess arms in the Town goal while Whitham scuffed a shot wide with the best of the chances before the break.
After the interval, with Marcus Carver withdrawn having taken a knock in the first half and Robbie McDaid entering the action, Chorley stepped up a gear with a vastly improved if not fully polished second forty-five.
Challoner and Sampson combined early on, but the full-back’s shot was charged down and from the second phase McDaid headed just wide.
Jarvis, looking to have fully benefited from his month on loan at Lancaster, was having a superb game but was unlucky when a jinking run into the box ended with Ryan Wilson clearing off the line.
With a little over 20 minutes to play O’Keefe replaced Whitham for the second Magpies substitution and within minutes was involved with a strong shout for a penalty when appeared to be pushed while going for a Challoner cross; the match officials were unimpressed with the appeal.
Sampson whipped a tantalising ball across the face of goal, but no-one could get on the end of it.
Will Beesley came on for Keiran Charnock and Matt Jansen shuffled his pack from a 532 to 433 with the pacey left-back deployed in an attacking role for that ten minutes.
As time appeared to be running out Jake Cottrell fired wide from distance following a corner in more desperation than expectation.
However, the never-say-die Magpies got the reward for their endeavours on 86 minutes. Man-of-the-match Jarvis cut in from the left and his shot was headed for the keepers left hand bottom-corner. Spiess managed to parry the shot, but only into the patch of Sampson who lifted the ball over the keeper for his fourth goal in just six games.
Not content with a point Chorley went looking for a winner and on 90 minutes Blakeman almost grabbed it but his 30-yarder shaved the bar.
However, in the fourth minute of added time a superb delivery from Jarvis was nodded beyond Spiess to secure the points and fourth place; in the absence of 5th 6th, 7th or 8th picking up any points todays win was all the more crucial.
Starting XI: Ritchie Branagan, Matt Challoner, Paul Jarvis, Andy Teague, Kieran Charnock, Stephen Jordan, Adam Blakeman, Dale Whitham, Marcus Carver, Jack Sampson, Jake Cottrell
Subs: Josh O’Keefe (Whitham, 68), Adam Roscoe, Waqas Azam, Robbie McDaid (Carver, 45), Will Beesley (Charnock, 80)
Goals: Liam Hearn (23), JACK SAMPSON (86), JOSH O’KEEFE (90+4)
Chorleyfc.com Man of the Match: Paul Jarvis, two assists rescued the points