Di Matteo spent six years as a player at Stamford Bridge and famously led the club to UEFA Champions League glory as manager in 2012.
The Italian was sacked by Chelsea just four months after that final victory over Bayern Munich, but says he bears no ill feeling as he prepares his Schalke side to face the London club in the Champions League this week.
Schalke sit second in Group G, three points adrift of Chelsea, ahead of the clash at the Veltins-Arena.
"Honestly, I am not thinking about Munich 2012 that much," Di Matteo said.
"I am a person who looks forward, not backwards, I live in the present, even though lots of people keep reminding me of that match.
"I spent many years of my life at Chelsea and still know many people who work there, players as well.
"But that's more a private thing and has nothing to do with my job. Tomorrow, we will focus on our work, nothing else.
"I have no thoughts of revenge, I had a wonderful time there with lots of wonderful people."
Schalke would move top of the group with a victory, but Di Matteo knows the Bundesliga team will have to play to the best of their abilities to take all three points against the Premier League leaders - who have not lost in any competition this season.
"Chelsea remain the favourite in the group," the Italian added. "It is very even besides that, everything is still open. We can still win the group.
"Tomorrow we have to put in a great performance and hope for Chelsea not to have their best day.
"They are unbeaten, bring lots of individual quality to the table and are well positioned. We have to play a top game to win this game."
