Barnsley midfielder David Perkins is facing at least three weeks on the sidelines with the hamstring injury he sustained against Derby.
The former Colchester, Rochdale and Morecambe man limped out of the 1-1 draw with the Rams last week and is unlikely to return until late this month.
Manager Keith Hill is confident he has a ready-made replacement available in Nathan Doyle, who stepped into the breach for the 2-0 home win over Coventry last time out.
The Tykes boss confirmed Perkins will not feature against Portsmouth after the international break and is not certain as to when he will be fully fit to feature.
Hill told the Sheffield Star: "Perks is definitely not going to be ready for that one, he's going to need more time to recover from his injury.
"It's a shame for Perks because he's done really well, but he's likely to be out for at least three weeks.
"But Nathan Doyle got a chance because of his injury and came in and did a really good job against Coventry at the weekend.
"Nathan's had to be patient for his chance, but I was pleased with the way he performed. He was excellent."