Albion boss Sami Hyypia is in the dark about when Dale Stephens will be available to increase his midfield options.
The January signing from Charlton has been sidelined since suffering ankle ligament damage against Yeovil at the Amex in April.
Hyypia said: "It's very difficult for me to say when he will be fit, because the medical department is not sure either how long it's going to take.
"It can go quickly and it can go well when he starts to do more and more but he can have setbacks as well.
"We need to go day by day, week to week. He has quality and he will add his quality to the squad when he's fit. Hopefully that will happen soon."
Fellow midfielder Nzuzi Toko is unlikely to start Saturday's first game of the season at home to Sheffield Wednesday after missing most of pre-season with a swollen knee.
The Congolese summer signing featured in a 1-1 friendly draw for the under 21s against Chelsea on Tuesday.
Hyypia said: "I think he needs minutes on the pitch. When you are out for part of pre-season it's not a good thing and he needs to get his fitness and his minutes on the pitch.
"I don't know yet how the squad is going to look on Saturday, which players are in and which players are out, but he definitely needs his minutes on the pitch now."
Goalkeeper David Stockdale also played in the Chelsea match ahead of his debut against Sheffield.
Stockdale revealed to The Argus last Saturday that he wanted extra game time to compensate for his inactivity during the close season with former club Fulham.