Cole to miss Shakhtar clash
The left-back missed training on Monday after picking up a hamstring injury, but Di Matteo said the injury is only minor.
"Ashley Cole won't be available tomorrow, he has a problem with his hamstring, but shouldn't be out for long," Di Matteo told reporters.
Di Matteo expressed confidence that Ryan Bertrand could deputise for the England international in the Group E clash at Stamford Bridge.
"Ryan Bertrand has always performed well for us when he's played and I have full confidence he will play a great game," the Italian said.
Di Matteo went on to warn his players that every one of them must be at their best if the Blues are to defeat the Ukrainian champions.
"We need to be at our best, every player has to perform to the best of their ability. The early goal in Donetsk helped them," he said.
"The team has a winning mentality and experience of performing in big games like this, which helps. We have very good players."