The Czech Republic international limped out of at half-time after sustaining the injury in mysterious circumstances early on.
"We will also be liaising with the Czech FA's medical department about Petr's injury. Hopefully the international break will allow time for the injury to improve."
Cech added: "I don't know exactly how it happened.
"I only know that I felt a pain from the 10th minute of the match. Nevertheless I played the first half.
"I feel bad that I will be out right now when myself as well as my team are both doing well."