Despite recent cup disappointments, Colwell's men are riding high in the Ryman League and a good display at bottom-of-the-league Corinthian Casuals on Saturday followed by maximum points against Merstham on Wednesday could propel them into the top six.
Colwell said, "We have not performed well in the cups and we have to look at the reasons why but our league form has been quite good.
"This is a crucial time for us. Two wins and everything will be great but two defeats and it is all doom and gloom. We need to pick up four points from the next two matches and if we can do that I will be pleased."
The Town boss, still smarting from Saturday's FA Trophy defeat at Crowborough, added, "That game confirmed a few things I already suspected. There were a few players playing that you would not want to go to war with and I told them at training this week."
Luke Denton, Chris Dicker and Gary Brockwell could be unavailable due to work commitments.
Ben Putland has university commitments and Danny Williams and Greg Manton are doubtful with ankle injuries.