Right-back Kane Vincent-Young will be out of action for a further six weeks having suffered a knee problem in training.
The 24-year-old last played a competitive game for the Blues in October last year with two groin operations ending his 2019/20 campaign early.
The former Colchester man returned in pre-season and was involved in early friendlies before suffering an achilles injury which he was close to getting over.
He was back in full training and was due to play in Wednesday’s planned friendly against Brentford’s B team which was postponed because of a waterlogged pitch.
However, he hyperextended his knee and will now spend a further six weeks on the sidelines.
Luke’s arrival mean we’re not going to see Kane Vincent-Young this season?
"Really gutted for Kane," first-team coach Matt Gill said as he stood in for manager Paul Lambert at this morning's press conference.
"He’s had a little setback in his rehab or returning to play. I’m so disappointed for Kane as he’s worked so hard to be back in and amongst it and help the squad and help the team.
"But unfortunately he’s had a bit of a setback. These things do happen when you’ve been out for a while and you’ve not played games regularly, you can pick up these little setbacks.
"I’m just really disappointed for Kane because he’s obviously a very good player when he’s playing but he’s also a really great lad.”
He added: "Kane’s setback is a knee injury, so separate to his last one. Like I said before, sometimes when you’ve been out a while you pick up these secondary injuries.
"It’s really disappointing for Kane himself let alone us, but for him, he’s worked so hard to get himself in really good shape.
"But knowing the lad, he’ll put it behind him and get on with his rehab and try and get back as quickly as possible."
Asked whether the one-time Tottenham trainee will be out for the season, Gill added: "Currently we’re looking at a few weeks and obviously we’ll take it from there.
"Obviously it takes a little bit of time to get up to speed once you’re back out on the grass. Currently it’s a few weeks and we’ll just have to manage the situation.”
The signing of another right-back, Luke Matheson, late in the afternoon on deadline day gave an indication thatVincent-Young’s long-awaited return may again have been put on hold.
The Londoner made a huge impression having joined from Colchester for £500,000 in August 2019 but managed only nine games before succumbing to his injury problems.