Cech, who missed three games last month with a groin injury, broke his little finger in what was an impressive display from the 30-year-old at St James' Park, despite the Blues being beaten in the Premier League clash.
It is not yet known how long the Blues goalkeeper will be sidelined, but it has been confirmed he will miss the Czech Republic's friendly against Turkey in Manisa on Wednesday after a scan revealed a fracture in his finger.
National team head coach Michal Bilek said he would play Dnepropetrovsk keeper Jan Lastuvka in the friendly against the Turks, with Hamburg's Jaroslav Drobny on the bench.
Cech told CTK: "2013 started unfortunately for me. At first it was groin, then calf and now the finger. Hopefully I have had my share of bad luck for the whole year already.
"I punched the ball and the head of one of Newcastle players at the same time. I thought it was nothing but went for an X-ray just in case. However, it showed there was a fracture."
Chelsea take on Sparta Prague in the Europa League later this month and Cech is not optimistic of recovering in time to face his former club.
"It will depend on whether we find a solution where it would not threaten my health and, at the same time, I would be able to perform adequately," added the 30-year-old.
"I have to be able to cover the shots, push the players away and so on. If I were unable to give 100 per cent, I would not play. With the splint I have now it would not be possible at all.
"I was waiting for 12 years to play against a Czech club in the European cups. If I should miss this chance, it would be ironic. I can't wait another 12 years, so I hope I will be ready to play."