St Johnstone frontman Joe Gormley is expected to get a scan after missing Saturday’s win at Ross County.
Gormley pulled up injured during the warm-up at the Global Energy Stadium and couldn’t take his place on the bench.
He felt discomfort in his knee and now Saints will investigate the matter further.
McDiarmid boss Tommy Wright said: “Joe will be assessed and probably go for a scan.
“So we will just have to wait and see what that says.”
The on-loan Peterborough forward missed nine months of last season with a cruciate ligament injury.
Wright has been without Tam Scobbie due to a knee injury for the last six weeks but he is ready to resume training soon.
Meanwhile, the 2-0 win over the Staggies moved Saints on to 14 points in joint third place alongside Hearts and they are ahead of where they were at the same stage last season.
Wright added: “It took us 11 games to get to 14 points last season so it has been a very good start to the season.
“I thought we were very good, especially in the first half, against Ross County so it’s great to go into the international break on the back of a win.”