The left-back was forced off 10 minutes from the end of the 3-1 defeat to Portsmouth in midweek with a groin injury and Robins boss Keith Millen has given McAllister a 50-50 chance of being fit for Saturday.
Defeat at Fratton Park was the third in a four-match winless run for Millen's men. Changes could be in the offing with Ivan Sproule, Jamal Campbell-Ryce, David Clarkson and the fit-again Danny Haynes and Brett Pitman offering attacking alternatives.
Defenders Damion Stewart and Nicky Hunt and midfielder Lee Johnson are other options for Millen.
However, on-loan Tottenham defender Steven Caulker is likely to keep his place and make his home debut.
Norwich manager Paul Lambert has an unchanged squad to choose from.
Lambert saw his side move up to third in the table on the back of Tuesday`s 4-3 victory over 10-man Leicester at Carrow Road, which saw only a second start for striker Simeon Jackson.
The Canada international was replaced by Chris Martin, who had dropped to the bench, with 19 minutes remaining, but who Lambert goes with remains to be seen.
Steven Smith made his first appearance for the club since joining from Rangers in the summer when he came on for the final 10 minutes against the Foxes but he is expected to again start on the bench.
Source: DSG
Source: DSG