Pompey are hoping Hermann Hreidarsson’s injury won’t rule him out for the remainder of the campaign.
The veteran defender hurt his left knee while blocking a Craig Bellamy cross in the first half of Saturday’s Cardiff defeat.
He didn’t reappear after the break, with Aaron Mokoena brought on as a replacement.
In his absence, 10-man Pompey went on to lose 3-0 to the promotion hopefuls.
With Ricardo Rocha suspended for the rest of the season, the Blues desperately need Hreidarsson in their defence.
In addition, his contract runs out at the end of the season with the club yet to offer him a new deal.
Steve Cotterill is keeping his fingers crossed the Icelandic international will be available for the Fratton Park clash with Swansea next weekend.
He said: ‘We lost Hermann at half-time, which was a blow because we needed his leadership skills out there and he is a tough boy.
‘At half-time he came in and we got some ice on his knee straight away.
‘We didn’t know whether he was going to stiffen up or not so had to give him the duration of the interval.
‘It did stiffen up so the decision (to take him off) was made literally two minutes before we went back out.
‘For Hermann to come off there has to be something wrong with him. We just have to wait and see with him now.
‘It’s a shame he had to come off because he’s got the heart of a lion. That’s one thing we needed.
‘We are hoping he is going to be okay. We need to see.’
Cotterill insists that injury blow hampered his substitute options as he attempted to find a way back into the game.
Carl Dickinson was also brought on, while Danny Webber entered the pitch in the 64th minute.
And the Blues boss revealed he would have liked the option to change his attacking impetus even more.
He added: ‘We were a substitute light, really.
‘We wanted to use our subs further forward but couldn’t because of Hermann’s injury.
‘Liam took a heavy challenge, too. We’ll just have to wait with them.
‘And it was a tough game, it’s tough on the lads when they are out there and having to perform against 11 players, a partisan crowd and I am not sure the officials gave us much either.’