Chesterfield will give Zavon Hines every chance to play a part in tomorrow's FA Cup replay at Billericay.
The Spireites striker returned from time off last week with a sore knee and didn't feature in the matchday squad for Saturday's game against Havant and Waterlooville.
Hines, 29, was unable to train this morning but Allen hopes he can contribute at Ricay.
"He's got a sore knee," said Allen.
"He's going to see how it is tomorrow and we'll do a fitness test when we get down there tomorrow afternoon.
"He didn't train this morning but because of his skills and what he brings, we'll give him every chance to have some involvement tomorrow night."
The former Bradford City man has three goals this season and has looked a threat for Town, who have struggled in front of goal during their nine-game unbeaten run.
They had 24 efforts on Saturday but were unable to find the net.
Allen admits Hines could be 'key' but says, longterm, they've got to sort the forward's knee issues.
"His knee hasn't been right, we've got to get his knee right," said the boss.
"Whether we can go from one training session a week and playing, on a regular basis...you can do that sometimes for a short period of time, but he's booked in to go for a scan.
"That's been cancelled today, to give him a chance to be with us tomorrow, it's now booked in for Thursday.
"It would be good to have him in our team."