Richard Chaplow and Tadanari Lee will be in the Southampton starting line-up.
Boss Nigel Adkins has confirmed Chaplow will make his comeback from a knee injury in midfield and Japan forward Lee will be handed a full debut up front.
New striker Billy Sharp is ineligible, Tottenham loanee Iago Falque is cup-tied, centre-half Jos Hooiveld has a hamstring injury and full-back Danny Fox is suspended after he was sent off at Birmingham on Saturday.
Adkins will make changes with Bartosz Bialkowski set to start in goal and Radhi Jaidi, Dan Harding, Lee Holmes and Lee Barnard likely to be involved along with youngsters Luke Shaw, James Ward-Prowse, Ben Reeves and Jack Stephens.
Millwall are set to be without their captain Paul Robinson.
The defender is close to recovering from a thigh injury but is more likely to return in the Championship clash with Derby on Saturday.
Striker Andy Keogh, the deadline-day signing from Wolves, is ineligible as he was not registered when the sides drew 1-1 in the original tie last weekend so Tottenham loanee Harry Kane or former Saint Dany N'Guessan will start up front.
Tony Craig, Chris Hackett, James Henry and John Marquis could be added to the squad after missing out at West Ham on Saturday but Hamer Bouazza, Jordan Stewart (both groin), Tamika Mkandawire (knee) and Therry Racon (ankle) are still out.