Speaking on 6PR on Monday night, Lyon revealed that his defensive stocks could be tested this week if McPharlin was unable to recover in time for the clash with the Tigers.
The Dockers are already without Michael Johnson for two to four weeks after he was subbed out with what was initially assessed as a medial ligament strain during their 40-point win over Adelaide last Sunday.
Lyon said McPharlin did have a scan but the Dockers are yet to know the full extent of the issue.
"It doesn't look great although I think we'll see how he pulls up tomorrow and we'll be able to update further from there," Lyon told 6PR.
"He played out the game. He hurt it early. We were a bit worried at half-time. It's a bit of an old injury.
"He played out really strongly and did the job on (Taylor) Walker. But if he's not right, Alex Silvagni will come in and take his role and (Garrick) Ibbotson has already taken Johnson's so we're pretty comfortable with it."
The Dockers have a testing 24 hours ahead of them with livewire forward Hayden Ballantyne to front the AFL Tribunal after the Match Review Panel opted to refer his bump on Matthew Jaensch.
