The 8pm kick-off is live on Sky Sports Main Event and manager Rob Edwards has made just the one change from Saturday's 1-0 away win against Birmingham City.
Reece Burke, who suffered an injury at the weekend, is replaced by Tom Lockyer who returns from his one-match suspension.
Morris was also forced off but is okay to start alongside Elijah Adebayo, just three days after scoring his 13th goal of the season at St Andrew's.
Club captain Sonny Bradley is back amongst the substitutes for the first time since November as Luton Town go in search of a second successive league victory.
Luton Town: Horvath; Drameh, Lockyer, Osho, Bell, Doughty; Nakamba, Mpanzu, Clark; Morris, Adebayo.
Substitutes: Shea, Bradley, Berry, Woodrow, Campbell, Onyedinma, Taylor.
Millwall: Long; McNamara, Cresswell, Cooper (C), Wallace; Shackleton, Leonard; Voglsammer, Flemming, Honeyman; Bradshaw
Substitutes: Bialkowski, Hutchinson, Evans, Burke, Malone, Watmore, Esse.
Referee: Geoff Eltringham