Victory will confirm Chelsea’s place in the Champions League’s knock-out phase, but the focus will be on Mourinho’s opposite number on the Schalke bench.
Chelsea coach Mourinho, the self-styled ‘Special One’, won the Champions League title as Inter Milan coach in 2010 and Porto boss in 2004, but the European crown has so far eluded him in his two stints at Stamford Bridge.
Premier League leaders Chelsea are unbeaten in their first 12 league matches — a club record — and strolled to a 2-0 win over West Bromwich Albion at home on Saturday with goals by Diego Costa and Eden Hazard.
Chelsea face Schalke in Gelsenkirchen as Group G leaders, three points clear of their second-placed German hosts, but the Premier League side have a much better goal difference.
Di Matteo has won all four of his home matches since taking charge of Schalke last month and is in his first role since being sacked by Chelsea in November 2012, just six months after winning the Champions League title.
Mourinho clearly did not like to be reminded that he will be up against the only coach to bring the Champions League to Stamford Bridge and insisted it is Chelsea against Schalke, not him against Di Matteo.
“I don’t play against him,” said Mourinho dryly.
“If I play against him, he wins because he plays better than me. Unless I am fitter, which I don’t know, but normally he wins because he is much better than me.
“It is Chelsea against Schalke, it is not me against Di Matteo.”
Schalke earned a point at Stamford Bridge in September, before Di Matteo took charge, when Cesc Fabregas’s early goal for the hosts was cancelled out by Klaas-Jan Huntelaar’s second-half equaliser.
– ‘Everything is still open’ –
Mourinho said his team’s aim is to finish top of their group and have their place in the knock-out stage confirmed as quickly as possible.
“The group is easy to analyse, we can finish first, second or third,” he said.
“To finish third and go to the Europa League should be something that would be against the evolution of this team.
“This team wants to be a very good team and to be a very good team you have to play against the best teams in the best competitions.”
Di Matteo’s Schalke enjoyed a 3-2 win over Wolfsburg on Saturday, which ended Wolves’ eight-match winning streak and pushed the Royal Blues up to seventh in the table.
The Italian, also a former Chelsea player, said there will be no room for sentiment on Tuesday.
“For me personally, I’ll just concentrate on my work of trying to win the game for Schalke. Chelsea also played on Saturday and they are in the same position as us in terms of recovery,” he said.
“We have the Champions League game on Tuesday where everything is still open and anything can happen, but we want to take at least a point from the home game.”
Di Matteo has said he is considering using the 5-3-2 formation which worked well against Wolves, with full-backs Atsuto Uchida of Japan and Austria’s Christian Fuchs given licence to attack.
It paid off initially as Schalke raced into a 3-0 lead with Cameroon striker Eric Choupo-Moting scoring twice and Fuchs firing home a free-kick before Wolfsburg fought back.
Chelsea have Costa back to full fitness with the 11-goal striker saying he is “totally recovered” from nagging groin and hamstring injuries after a fortnight of rest during the international break.
“It’s easy to see the difference in him now. He can run, he can sprint, he can get behind people, he can challenge for every duel,” Mourinho said.
“It was very important for him to have these two weeks to recover properly.”