New signing from Darlington, Greg Taylor, is cup-tied for the game and striker Stuart Fleetwood is ruled out through suspension, while Freddie Murray (knee), Ed Asafu-Adjaye (foot), James Dance (cheek) and Tommy Wright (ankle) are all out injured.
On the first two, Brabin said: “It’s disappointing, but we don’t expect it all to happen overnight. We are getting all of our players back on the pitch and it’s a good chance for people to come to the fore in a big FA Cup game and we will have those players available again next week.
“Definitely out would be Freddie and Ed and James Dance is fresh from his facial operation.
“It’s gone well, he has come in eager looking a bit like the elephant man but he is still better looking than half of our players.
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“He’s come back in and wants to go straight back into the squad which I’m delighted with that kind of attitude.
“It wouldn’t be fair for me to even include him. He will probably hate me for it and come knocking on the manager’s office. I think it’s too soon. He’s had the operation on Tuesday, come out of hospital on Wednesday and is training with us on Thursday.
“He is probably going to be disappointed not to play tomorrow.
“Tommy Wright twisted his ankle in the reserve game on Tuesday after the first few minutes and won’t be available for tomorrow.
“One of the things we’ve said since the start is I want to get our players fit on the pitch and we’ve got to start performing a bit more consistently and getting some more consistent results be that FA Cup games or league games.
“We need to start getting a little more consistency in our results and our performances. Again with the FA Cup I’m a bit of a traditionalist so want to do as well as we can in the FA Cup.
“Obviously we’ve got our aim of being promoted as well in the league so I think they tie in quite well together.”
New signing Taylor was disappointed to miss out against one of his former sides, saying: “A little bit, but that’s the luck of the draw having played in the FA Cup.”
Fellow former Cobblers defender Dean Beckwith, meanwhile, is keen to play against the club he left in the summer, but Brabin is adamant he will name the strongest side available to him, like he did in the 5-1 thumping of Hendon in the previous round.
He continued: “I never mixed it up against Hendon, I named my strongest side possible. The only player I rested was George Pilkington and Mark Tyler. I certainly never took that game lightly and I won’t be taking this one lightly either.
“We know they are not a bad side but they haven’t done as well as they probably anticipated. They’ve got a good proven manager at the helm and I’m more than confident that someone like Gary (Johnson) will turn Northampton’s future around we just hope he doesn’t do that on Saturday.
“I keep saying this is a competitive game and I think we are a good side, and we can definitely more than compete against teams in higher divisions.”
Northampton are fifth from bottom in League Two and coming off the back of a 4-3 defeat at Gillingham.
Brabin continued: “I think it was just a bad day at the office and we won’t be pinning out hopes on that one day.
“I think it will be a good positive atmosphere. I think it’s good to have a break from the league and we should have a good crowd and there’s always a good atmosphere in derby games. It’s the closest we’ve had for some time as a derby game. I’m sure both sets of supporters will enjoy it.
“We are quite attack-minded and won’t change it on the day.
“We will be aware of their strengths and weaknesses. We will be playing our normal game.”
And Brabin is also looking for his side to bounce back from the disappointing 2-1 home defeat to title rivals Fleetwood Town.
He added: “It was disappointing. It’s gone now. We’ve got to get our own house in order. We know we have a good group of players. We’ve strengthened that with the left-back situation and it would be good if we could build on that with a nice win on Saturday for the forthcoming weeks and games.”