The 29-year-old Czech Republic international suffered a medial ligament strain after a heavy fall and is expected to be out for three to four weeks, Villas-Boas told reporters.
The injury means Cech will definitely miss Chelsea's upcoming Premier League games against West Brom and Norwich.
"Petr Cech yesterday suffered a medial ligament injury and will be out for three to four weeks," Villas-Boas said.
"It was the end of training, a normal training incident. He fell awkwardly with his weight on top of him.
"We expected much worse when we saw the incident."
Source: AFP
Source: AFP