The European champions crashed to a 2-1 defeat to Shakhtar as John Terry's return to the side went awry at the Donbass Arena to leave them facing a real fight to qualify for the knockout stage.
Previous holders have never failed to do so and Di Matteo acknowledged Chelsea now had to win their home games against Shakhtar and Nordsjaelland to maintain that record. The Blues boss said: "We need to win our two home games remaining for sure."
"The consolation is that Juventus drew in Denmark," he added. "It just shows how the Champions League is a very competitive competition.
"But certainly, we need to win our home game against Shakhtar."
The defeat left Chelsea three points behind their opponents in Group E and they were only spared dropping to third place by Nordsjaelland's shock draw with Juventus.
Di Matteo's men were almost completely outplayed, their outstanding opponents punishing them with goals early in each half from Alex Teixeira and Fernandinho before Oscar bagged a late consolation.
"They're a very good side," Di Matteo said of a team that had never lost at home to English opposition and had not been beaten at all for exactly 11 months.
"The early goal helped them massively and it's always difficult when you concede such an early goal in a big game like that. It did unsettle us a little bit as well and, (in the) first half, we never really got into our rhythm.
"In the second half, we came out better and started to get into the game and controlling the game a little bit more. And then we got caught in possession on halfway and they punished us with the second. Then, you're chasing two goals and the game becomes very open."
Source: PA
Source: PA