Scott Fitzgerald's Bees are three points adrift of safety, while Northampton are hovering just above the drop zone.
Brentford will feel the more confident of the two though, after securing their third consecutive League One victory with 1-0 win at Huddersfield on Saturday.
Northampton have been in freefall in recent weeks, and needed a late equaliser against Gillingham on Friday to avoid a fifth defeat on the trot.
Strike duo Jo Kuffour (calf) and Charlie Ide (hamstring) were both substituted for Brentford at the weekend and will be assessed prior to kick-off, while left-back Sam Tillen is also doubtful after suffering concussion.
John Mousinho missed the game against Huddersfield after failing a late fitness test and is racing to be fit in time for Northampton's visit to Griffin Park.
Ian Taylor could be recalled for Northampton, while Jordan Robertson is also in contention to start after scoring as a substitute against Gillingham.
David Hunt collected his fifth yellow card of the season on Friday, but his suspension does not begin until this weekend.
Sky Sports