Southend striker Francis Laurent has suffered a recurrence of his ankle injury during Tuesday's reserve loss at Leyton Orient.
The Frenchman was substituted after 52 minutes after making his return following over five weeks out.
However Blues reserve team boss Ricky Duncan is playing down the seriousness of the latest setback and told the club's official website: "There wasn't too much swelling and he iced it right away."
He added: "Francis was going to come off anyway because it was his first game back and hopefully the injury isn't too serious.
"We will find out more in the next couple of days."
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