Barring long-term injuries, Lee Baker had an almost full squad to select from but was forced to make a late change to the starting XI when Cameron Ross suffered an injury in the warm-up and was replaced by Kieran O’Connor.
Garstang were almost undone by a long diagonal ball over the top with an audacious lob from 25 yards going just over Will Kitchen’s goal.
Jake Salisbury’s shot flew just wide as Garstang started to apply more pressure and win a series of corners which tested the hosts’ defensive capabilities.
It became one corner too many for Chadderton on the quarter-hour when Tom Graham whipped in a cross and O’Connor timed his run perfectly to get in front of his marker at the near post and nod home.
Ric Coar could have extended the lead when found by Jack Swindlehurst but his shot was well saved by the Chadderton keeper, who made a brilliant stop to keep out Jonny Hothersall’s 25-yarder.
The home side got back into the game with a great team goal on 34 minutes, moving the ball quickly between their midfield players and then setting up William Shawcross, who got behind the Garstang back line to finish smartly.
The scores were only level for a short period of time when Garstang retook the lead as Dan Birch pulled the ball back into Ric Coar’s path for a close-range finish to make it 2-1 at half-time.
However, with the second half only five minutes old, Garstang gave away a needless free-kick.
It was floated to the back post and, with the defence and keeper failing to deal with it, the unchallenged James Dwyer scored with a simple header.
That goal seemed to drive Chadderton on and Garstang were increasingly unrecognisable from the first half.
The home side then took the lead for the first time on 75 minutes when Billy McKenna failed to hold the ball up and Chadderton countered quickly with Joseph Richards unleashing an unstoppable shot from 30 yards which went in off a post.
Omar Camara then doubled the lead from close range on 80 minutes as Chadderton took an unassailable lead in a game that Garstang had looked the likelier team to win in the first half but, in the time remaining, the Riversiders were unable to trouble the home keeper.