Scotland captain Budge Pountney looks set to miss the Six Nations clash with Italy on Saturday.
The Northampton flanker missed the 20-10 Premiership defeat to Sale at the weekend with an abdominal muscle strain.
Club physio Phil Pask said Pountney's inclusion for the game in Rome is "highly unlikely".
"He may not join them this week as he's got to rehabilitate the injury for another four or five days, so he won't be able to train with any power or pace," said Pask.
"He's upset and disappointed, as he was just getting into a run of form after his shoulder injury."
Northampton team-mate Tom Smith is likely to deputise as captain as he did in the autumn Test series against Tonga, Argentina and New Zealand.
Pountney lead the side in their 29-3 Calcutta Cup defeat to England at Murrayfield.
Should he fail to recover, the experienced Martin Leslie, on the bench against England, is likely to step into the openside role.
PA