The goalkeeper has only just returned from an ACL injury, but Ancelotti admits a bout of flu copped by Andriy Lunin means the Belgian will play.
He said, "Lunin has been suffering from flu and hasn't been able to travel or train . He's travelling tomorrow and will be on the bench, so Courtois will start."
Ancelotti continued: "We've had the time we need to prepare for the game. The team is focused and concentrated, in the dressing room there is the necessary confidence to be at our best. We have to be confident to play the most important game of the season. We always have a lot of respect for our opponents, who fully deserve to have reached the final. Let's hope that everything goes well.
"I'm very happy to be here, it's not the first time and hopefully not the last. We've had a good time in the run-up to this type of match. Afterwards, there will be the usual pre-match jitters, but I'm confident. I know my players will give their all, as will Rodrygo. He's a very important player for us and will be in the future, we have no doubt about that."
On his approach to the clash, Ancelotti said: "For me the most important thing in this type of game is to get clear ideas in the players' heads about what to do on the pitch. When I'm clearer, the team is less nervous, I will focus a lot on the tactical aspect. Emotions come and everyone handles them with the character they have. We will have negative emotions before the game of fear and worry, but they're an important part of doing things well.
"I'm very confident because the team has shown fantastic quality throughout the season. Another very important component is the collective sacrifice and attitude. This team has been able to show that throughout the season. Sacrifice and quality will be the key for tomorrow.
"One thing is playing this type of match, which is the most important match of the season. And another thing is that we're playing at Wembley because it's a historic stadium. We're happy to play here and we hope our team will be at its best tomorrow."