Oli Hawkins will undergo a scan on his hamstring injury today.
Meanwhile, Pompey boss Kenny Jackett is hopeful Kal Naismith's knee complaint isn't as bad as first feared.
The duo were forced off in the second half of Saturday's 1-0 win against Plymouth.
Hawkins, who was operating in a central-defensive role, limped off on 59 minutes after aggravating his hamstring.
He is in London this afternoon to have tests to assess the extent of his injury.
Goalscorer Naismith was substituted after 83 minutes following a collision with Pilgrims keeper Remi Matthews.
Speaking at his press conference today, Jackett said he shared the same positive attitude and was hoping for good news on both players.
He said: 'Hawkins will have a scan.
'He's gone for a scan this afternoon in London, so hopefully we'll know tomorrow how bad his hamstring is. Hopefully he's not too bad.
'Kal Naismith, it was just a pure contact injury which everyone in the stadium saw
'It was a collision with the goalkeeper which was brave and resulted in him hitting the post.
'We hope in a few days that can settle down and he can come through.
'We're hoping for some good news.
'We wouldn't want to lose anybody but we certainly wouldn't want to lose those two for any period of time.'