Gareth Hill scored twice in the last 15 minutes as Nelson came from a goal down to beat Garstang 2-1 at Little Wembley on Saturday.
Garstang made the short journey with Lee Baker’s side looked to extend their unbeaten run to eight games.
But Andy Harrison’s side had other ideas.
The rain started to fall as the game kicked off, and, as the half wore on, the pitch got progressively worse, which made football very difficult for both sides.
Billy McKenna whipped in a number of good crosses for Garstang, which Nelson dealt with, and they restricted the service to Ric Coar and Jake Salisbury.
Nelson had a couple of good efforts at goal, one of which was brilliantly saved by Will Kitchen low down at his front post from Hill, from a cross from debutant Taranjeet Jheeta.
Garstang almost took the lead when Coar was found by Salisbury inside the 18-yard box, and, with his back to goal, Coar brilliantly turned his man and shot on the turn but his effort went just wide.
Ross also had a header cleared off the line from a corner, but the game remained very even and, at half-time, it was goalless.
At the restart, the Riversiders had more attacking menace, as Salisbury and Coar started to create problems and keeper Marcel Wusiewicz was called into action on a number of occasions as Garstang looked the team most likely to break the deadlock.
The Riversiders eventually took the lead in the 60th minute when Salisbury chased down a long ball and shot home from just inside the box.
Coar then missed a great chance to kill off the game when he shot straight at the keeper from close range.
By this time, the rainfall was like a monsoon as the pitch turned into a mudbath with the game becoming a lottery for both sides.
Kitchen once again made two great saves, one of which was from a tremendous 30-yard effort from Alex Grice that looked destined for the top corner.
Nelson equalised with 15 minutes remaining when a corner came in from their right-hand side, and Hill headed in from close range.
Nelson used the appalling conditions to their advantage and closed down Garstang at every opportunity high up the pitch.
The pitch had now become unplayable, and with the clock ticking down, the home side scored the winner when Hill got free down the inside right channel and shot home past Kitchen.
Tuesday night’s home game against Carlisle City was postponed.
The Admirals are due to host Prestwich Heys tomorrow at Little Wembley (3 p.m.), before travelling to the Stafflex Arena on Tuesday to face Shelley (7-45 p.m.).