Cech underwent surgery after suffering a skull fracture and Terry may need to go under the knife to fix back problems.

"To lose Petr and John at the same time is a very difficult problem to solve, especially in a squad without more central defenders," Mourinho was quoted as saying by BBC Sport.

The Premiership winners also lost French international defender William Gallas and German center-back Robert Huth in the summer.

Gallas joined Arsenal on a deal that sent Ashley Cole the other way while Huth signed for Middlesbrough.

"We sold Gallas and Huth in the summer. We don't have enough cover so at this moment in time we are having problems," the Portuguese manager said.

Chelsea conceded six goals in the last three encounters and this, according to Mourinho, put more pressure on the attacking line.

"For us to win matches right now we need to score three times. Sometimes we'll do it, sometimes we won't," he said.