The Gills managed their first win in four matches by impressively defeating second-placed Peterborough United 1-0 at the London Stadium.
With three games of their season remaining and them being out of the play-off race they will aim to secure a top-half finish instead.
Northampton, who occupy the last relegation spot, also got their first win in four with a confident 3-0 victory over Ipswich Town.
Northampton right-back Peter Kioso could be a doubt for the weekend as his groin injury continues to cause him issues.
Bonham; Jackson, Cundy, Tucker, Ogilvie, Graham, Dempsey, O'Keefe, MacDonald, Lee, Oliver.
Northampton Town (4-3-3):
Mitchell; Harriman, Horsfall, Jones, Mills, Morris, McWilliams, Watson, Hoskins, Jones, Chukwuemeka.
Gillingham have been a little inconsistent of late, having won two out of their last five.
Their play-off challenge has effectively ended with two defeats and a draw before they got back on track with the Peterborough win.
Despite only being four points off Charlton Athletic in sixth place, they have played more games than everyone around them, so it would take a miraculous turn for them to end up there.
Northampton have been similar to the Gills in their inconsistency of late having also won just two of their last five.
They will need to find some wins in their last three matches if they are to catch up to either Wigan or Wimbledon and secure their status in League One for another season.
Ones to watch
If Vadaine Oliver starts, he'll be the one to watch for Gillingham.
The striker is physically proficient in the air and is enjoying in the best scoring season of his career, having netted 17 times in all competitions this campaign.
Sam Hoskins will most likely be the one to watch for Northampton.
The striker has popped up with some crucial goals in the last couple of months and has overall provided the most goal contributions in the squad, with seven strikes and six assists. He'll be a threat that the Gills defence will need to be wary of.
The most recent fixture between the two teams came earlier this season in December 2020. Northampton defeated Gillingham 3-1 that evening, with a penalty from Sam Hoskins and further efforts from Danny Rose and Alan Sheehan being plenty enough to overcome Kyle Dempsey's free-kick.
In the overall head to head record Northampton also lead the way with 53 wins compared to the Gills' 42. There have also been 19 occasions where the points have been shared between the two sides.
How to watch
The game has not been selected for TV coverage in the UK, but an iFollow pass can be purchased for £10 via either club's website to stream the game live.
Kick-off is scheduled for 15:00 BST.