"It was a bit of a baptism for Gary," he said.
"He has not played much in the Champions League and it was a difficult game. But I am very pleased that he played so well, as did the whole back four."
Chelsea were forced to survive a few scares but Di Matteo said that was only to be expected under the circumstances.
"Sometimes it feels like they have 20 players," he said.
"They have a unique style of play, with quality players. They are the only team in the world who can do that."