The former Porto boss unveiled Di Matteo, who spent six years at the club as a player before injury forced his retirement in 2002, as his assistant manager last week.
The 41-year-old acted as manager for West Bromwich Albion until he was sacked in February, despite bringing them back to the Premiership.
“It's obviously a challenge for me, but I don't anticipate any problems,” he told Chelsea’s website of his title change. “I've got experience of being a manager, I know what it is like, and I know what it is to be a coach, so I have a bit of both and I am there to support Andre and any of the staff, to give what it takes for us to be successful. That's the ultimate challenge.“
The Italian added that he experienced “a good link and a good understanding” when he met with Villas-Boas, and said that they share a similar approach to the game.
“His call came a bit out of the blue to be honest, so it’s mostly based on the fact that he likes my football philosophy and that’s why he wants me to be part of his team,” he said.
“I think he likes to play football and be positive and attacking, and over the years if you've seen a game or two of the teams I coached I think we played the same way, I liked my teams to try and win games rather than not lose, to build, to pass. He's going to be in charge of it and we're going to be working the way he thinks is the right way to be successful.”