The American international limped off during the Premier League defeat to Manchester City on Thursday and duly missed the FA Cup capitulation at the hands of same opposition four days later.
Raheem Sterling is now set for a scan on a hamstring problem picked up against City, while Pierre-Emerick Aubameyang missed Sunday’s defeat with a minor strain.
Standard Sport understands members of the Blues squad are growing increasingly concerned about the situation.
Club doctor Paco Biosca and head physio Thierry Laurent left Stamford Bridge during the wide-scale restructure following May’s takeover, with the Boehly-Clearlake regime believing Chelsea’s Premier League rivals boasted a more progressive medical department.
The issue, however, is yet to have been resolved.
Speaking after defeat at the Etihad Stadium, Potter said: “Christian just opened up his knee in the game the other day so we’re still analysing it. It’s going to be weeks I would say.
“Raheem just had an action in the first minute that game, a back heel that was a bit strange and he felt something in his hamstring.
“So again we are analysing that. Aubameyang had a tight back yesterday so was unable to travel.’