Boss Michael Appleton, who gave debuts to 11 players in Saturday's 1-1 draw with Bournemouth, is due to bring in winger Jordan Obita on a month's loan from Reading.
And Appleton is also hoping to receive international clearance to sign midfielder Liam Walker in time for the match.
Walker earned himself a trial with Pompey after impressing while playing against them for Gibraltar during the club's pre-season tour of Spain.
It means Appleton's squad is now up to 17, so he will almost be able to fill the substitutes' bench.
Former Barnet striker Izale McLeod continues in attack after his debut goal against the Cherries.
Colchester manager John Ward is set to name an unchanged team as his side seek to build on the weekend's draw against Preston.
The U's had goalkeeper Mark Cousins to thank as they managed to record a 0-0 draw at Deepdale, but Ward will keep faith with his team as they prepare for their first home game of the season.
Ward made four changes for the clash against the Lilywhites with Matt Heath, Freddie Sears, Marcus Bean, and John-Joe O'Toole replacing Tom Eastman, Kem Izzet, Andy Bond, and Drey Wright.
But the quartet who lined up against Yeovil in the Capital One Cup are unlikely to force for a starting place after going down 3-0 at Huish Park.
Ben Coker's dead leg will again be assessed with the left-back having not yet made an appearance for Colchester this season.