Murphy was not part of the matchday squad against Russia on Friday, with Coventry's Westwood on the bench to provide cover for the Manchester City keeper Shay Given.
A face injury, suffered in training on Sunday, has ruled Westwood out of the match in Bratislava on Tuesday night.
Giovanni Trapattoni, the Ireland coach, has added the Ipswich Town keeper Brian Murphy to the squad but Joe Murphy will be in prime position to claim a place on the bench.