Portsmouth midfielder Liam Lawrence has torn a calf muscle and is using an oxygen chamber to speed up his recovery.
Lawrence suffered the injury during last week's 1-0 victory over Barnsley when he was forced out of the game just before half-time.
The Republic of Ireland missed Tuesday's home win over Crystal Palace and is a doubt for Saturday's trip to Ipswich Town.
Pompey boss Steve Cotterill has not put a timescale on Lawrence's comeback, but outlined the measures being taken to boost the 29-year-old's prospects of a swift return.
"Liam will be back in on Thursday for us to look at him," said Cotterill.
"I have to see with that one. It's day to day with Liam at the moment.
"The injury's a tear, it's how long it takes to sort that. He's in the oxygen chamber every day and that will help speed up the process of recovery."