Vice-captain Joe Edwards has been ruled out for the rest of the season with an anterior cruciate ligament injury.
The versatile midfielder, who has scored seven goals in 34 appearances this season, sustained the injury in the second half of Saturday’s 2-1 defeat against league leaders Blackburn.
“Joe’s got a long term knee injury,” revealed manager Jon Whitney.
“We’ve had some devastating news this week. It was very innocuous but it will be long term.
“He’s seeing a knee specialist on Friday and we’ll know more after that.
“He’s definitely out for the season and probably the start of next season as well.
“All our thoughts are with Joe because it’s a devastating blow for him and for us as a group.
“The kid is feeling it. We’re thinking it’s an ACL rupture but we just want it to settle down before we see the specialist."
Whitney confirmed the news after last night’s 2-1 defeat at Peterborough, played in arctic conditions at London Road.
Julien Ngoy gave the Saddlers a ninth-minute lead but goals from Omar Bogle and Jack Baldwin secured victory for managerless Posh.
“Defensive errors cost us,” bemoaned the boss.
“On a pitch like that, you’ve got to use your nous and realise you’ve got to play the conditions.
“We said it was going to be a night of mistakes – and it was.
“I thought we created enough to get something from the game, especially first half, when we played really well.
“I’m disappointed with the goals and we gave ourselves a mountain to climb.
“The conditions were the same for both teams – we got done by costly errors.”