Wigan defender Maynor Figueroa is facing seven weeks on the sidelines with a knee injury.
Figueroa sustained the knee problem during last weekend's win at Burnley.
Wigan feared the injury might have been more serious and Latics boss Roberto Martinez admitted it was a major blow to lose the full-back.
"Maynor has had a second scan and we now know he has a tear in the medial ligament in his left knee," said Martinez.
"It is not as bad as we feared at the beginning. He will be out for between six and seven weeks.
"Maynor is a strong man and very fit. We will support him as much as we can.
"It is a big blow when any player is injured as we have a small squad and everyone has a massive role. But it is part of football and you have to cope."
Wigan could also be without Paul Scharner at Portsmouth on Saturday as he has a hamstring injury, while goalkeeper Chris Kirkland remains troubled by a dislocated finger.