Di Matteo decided to leave experienced trio Frank Lampard, Didier Drogba and Michael Essien out of his starting line-up along with England striker Daniel Sturridge for the fifth -round replay, but he is adamant all the players are "on board" for the challenges they will face in the next two-and-a-half months.
Di Matteo said: "Was it a brave selection choice? It was nothing to do with bravery. They were all on board. They know the targets we have to achieve."
He added: "We faced a difficult task today given the events of the last couple of days and it was important for us to get through to the next round. We had to do a job today.
"They are big players for this club. We have a squad and we have to utilise the squad. We have to try and get the best out of these players. It was a question of freshening up the team a bit, giving it some energy and fresh legs for a game like this. We had to fight today."
Di Matteo, who is in charge for the remainder of the season, admitted: "It has been a difficult time. It's been difficult for the whole club. When events like this happen... we've lost a great guy (Villas-Boas).
"But you have to deal with it. Tonight we had to focus on this game and move on as a club, put it to one side and move forward."
One bonus for Di Matteo was the return on the bench of skipper John Terry just two weeks after undergoing knee surgery.
Di Matteo said: "John has done very well and is determined to help the club, and we're pleased to see him. He's available.
"We have to take him with small steps because he's done well to come back in just over two weeks. But it was good to see him."
Source: PA
Source: PA