The European champions crashed to a 2-1 defeat to Shakhtar on Tuesday 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.
"We need to win our two home games remaining for sure," the Blues boss said.
"The consolation tonight is that Juventus drew in Denmark.
"It just shows how the Champions League is a very competitive competition.
"But certainly, we need to win our home game against Shakhtar."
Tuesday's 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."
Di Matteo admitted Chelsea did not defend well enough, although his game plan went out of the window when Frank Lampard's record 100th European appearance for the club ended after just 15 minutes. The midfielder suffered a recurrence of the calf injury that kept him out of England's World Cup qualifiers against San Marino and Poland and which now threatens to sideline him for Sunday's top-of-the-table Barclays Premier League showdown with Manchester United.
"We have to wait until we have a scan tomorrow to assess the extent of his injury," Di Matteo said.
"He was training with us fine and there were no alarm bells before the game." Di Matteo added:
"We started Frank, and with Ramires on the right, to try to control the midfield better.
"You find yourself 1-0 down and you have to make a change because of an injury.
"I thought it was the right choice to put on [Eden] Hazard and I think it was a question of us being too individualistic in our pressing in the first half and too long and too stretched as a team, and that conceded space to Shakhtar."
Terry suffered a nightmare start to his first game since accepting his four-match ban for racially abusing Anton Ferdinand when he unwittingly set up Shakhtar's opener. But he was otherwise arguably the least culpable of Chelsea's players tonight.
"The players were fully committed and JT played a good a game," Di Matteo said.
"I thought, as a team, we probably can perform better than we did tonight but I had no concerns about him before the game."
The Italian also shrugged off another hopeless performance in front of goal from Fernando Torres and warned Shakhtar Chelsea would be a different prospect at Stamford Bridge.
"I'm confident, at home, it will be a different game for Shakhtar and we are also very strong at home," he said. Shakhtar boss Mircea Lucescu had no doubt his side would win.
"We wanted to outplay their team and we've done it this evening," he said.
"Of course, Chelsea are one of the most beautiful teams - one of the most beautiful rivals - but we were sure we'd win and we've done it this evening both tactically and physically. "The opponent was rather strong but we really deserved this victory and we are rather content about the result of this game."
Source: team_talk
