Luiz has not played since last month's FA Cup semi-final while Cahill has been sidelined since suffering a hamstring injury in the Blues' epic semi-final victory over Barcelona in the Camp Nou.
With John Terry and Branislav Ivanovic both missing next Saturday's date with Bayern Munich through suspension, Di Matteo will be forced to field a makeshift back four if Luiz and Cahill fail to regain fitness.
"Now we're trying our hardest working towards next Saturday in the hope they'll be in the group training next week," said Di Matteo.
Both Luiz and Cahill will miss Chelsea's final Premier League game of the season against Blackburn on Sunday.
"They're at similar stages - not available for Sunday, and next week we'll push them to be available for the group," Di Matteo said.
Di Matteo is determined to give each player as long as possible to prove their fitness for Munich however.
"They've been out three or four weeks, not like three or four months. We have to push them as hard as we can," he said.
"I have next week to make those assessments. It'll be like that in the last couple of days, to see what level they reach."
Source: AFP
Source: AFP