It was Di Matteo who led the Blues to their one and only Champions League triumph in 2012, when they at the Allianz Arena. That is history, though, and the Italian coach insists "there's no time to be sentimental", particularly not when the stakes are as high as they are on Tuesday.
bundesliga.com sets the scene for what promises to be a humdinger of a game in Gelsenkirchen...
Failure to beat Sporting away from home on Matchday 4 means Group G is now wide open with Schalke, currently second, able to deny Chelsea premature qualification with a win at the Veltins Arena while ensuring they will go into their final group game at NK Maribor with their destiny in their own hands. The west Londoners, meanwhile, are through with a win.
(pictured), who missed Saturday's 3-2 win over VfL Wolfsburg through suspension, is available again, giving Di Matteo an extra option in defence. Otherwise, the Italian has the same players at his disposal on Tuesday night as he did in the victory over Dieter Hecking's charges on Matchday 12.
Cesc Fabregas is fit to play for Chelsea after shaking off the hamstring problem which ruled him out of international duty for Spain. Loic Remy is also fit again after putting a groin injury behind him, leaving Mourinho with a fully-fit squad to choose from, including former Bayer 04 Leverkusen forward Andre Schürrle (pictured, r.).
's brace ensured Schalke took the spoils against Wolfsburg at the weekend and the Cameroon international insisted in an exclusive interview with bundesliga.com that he felt at home in the new style of play employed by Di Matteo. Alongside Klaas-Jan Huntelaar, he forms a razor sharp Royal Blue attack.
The man Schalke will be trying to stop is Diego Costa (pictured), who netted his 11th goal of the Premier League season at the weekend. One of the candidates for the 2014 FIFA Ballon d'Or, Costa has yet to open his account for the Blues in Europe this term, making him even hungrier to do so on Tuesday.
Di Matteo (Schalke coach, pictured): "I had a great time at Chelsea, but there's no time to be sentimental - this is Schalke against Chelsea, and I want Schalke to win."
Jose Mourinho (Chelsea coach): "Obviously it would be better for us to qualify tomorrow. It'd be good for us to avoid a decider in December."
Schalke's form has been hot and cold, depending on their location. At home, they have won four out of four since Di Matteo took charge, including a 4-3 win over Sporting Clube de Portugal. Away, though, they have lost three out of three, including the 4-2 defeat in Lisbon which makes Tuesday's game all the more important.
These two sides are meeting in the group stage of the Champions League for the second season running, and the Royal Blues will be hoping history does not repeat itself. Last season, they lost 3-0 both home and away to the Blues, although their draw in London on Matchday 1 has already gone some way to ironing that out.
Schalke: Fährmann - Uchida, Höwedes, Felipe Santana, Aogo - Höger, Boateng, Neustädter, Fuchs - Choupo-Moting, Huntelaar
Chelsea: Cech - Ivanovic, Cahill, Terry, Filipe Luis - Fabregas, Matic - Schürrle, Oscar, Hazard - Diego Costa