Defenders Kgosi Ntlhe and Peter Grant (knee) both remain long-term absentees while loanee Saido Berahino's recent return to West Brom leaves Ferguson short of attacking options.
Fellow striker Tyrone Barnett returned to London Road earlier this week but is ruled out for up to three months after suffering a serious knee injury while on loan at Ipswich.
Ferguson was unable to name a recognised striker on the bench for last weekend's defeat to Middlesbrough as the division's bottom club suffered a third straight defeat.
But the Posh chief insists his side head to Wales looking to secure all three points.
"We'll go there and play the same way - we'll go and try to win the game," he told the club's official website.