Albion are likely to be without Bruno for the fourth match in succession at Birmingham on Saturday.
The Spanish right-back’s hopes of a comeback from injury at St Andrews have been hampered by the cold weather.
Manager Gus Poyet said: “The harder the pitches the less he can train, because it is an Achilles injury.”
Bruno, left, has missed five of the last six games with the Achilles problem.
Compatriot Inigo Calderon will deputise again at Birmingham following his return from knee trouble in last Saturday’s 2-1 home win against Derby.
Albion are giving a trial with the development squad to 17-year-old Plymouth goalkeeper Christian Walton.
Several Premier League clubs have been linked with Walton, including Southampton and Fulham.
Jake Forster-Caskey made his first appearance since returning from a loan spell with Oxford in a 1-0 friendly victory for the development squad at Bournemouth yesterday, secured by a goal from fellow midfielder Anton Rodgers.