Rangers goalkeeper Alexander has been ruled out of Saturday's penultimate Group 9 clash with FYR Macedonia after taking a slight knock in training but he remains part of the squad. Uncapped Aberdeen stopper Langfield had lost his place in George Burley's party following the return from injury of Craig Gordon.
Neither Alexander, 31, nor Langfield, 29, are unlikely to play a part in either Saturday's game or Wednesday's clash with Holland. Gordon is Burley's undisputed number one, while David Marshall deputised for the Sunderland keeper in last month's 4-0 defeat in Norway.
Alexander will be reassessed on Sunday to determine whether he remains with the squad for the Holland match. Scotland have already lost Burnley captain Steven Caldwell and Kilmarnock striker Kevin Kyle to injury, with Birmingham forward Garry O'Connor already drafted in as a replacement.