Will he pick Andriy Lunin, who has played in goal nearly the entire season, or Thibaut Courtois, the veteran who has won the Champions League before but has just returned from injury?
"It's really difficult," Ancelotti said Monday. "Of course it's really difficult, because both of them deserve to play this final. Lunin because he did a fantastic season, and Courtois because he is back from his injury and everyone knows the quality of Courtois. It's a difficult decision but I think I'm going to take into the game this decision, no doubt."
Lunin was nursing a fever and was the only Madrid player who didn't train on Monday as Madrid began its final week of preparations. But Ancelotti said the 25-year-old Ukrainian was expected to be available for Saturday's final in London.
The illness surely doesn't help Lunin's chances, though, and many had already expected Ancelotti to go with the more experienced Courtois despite his lack of minutes this season.
Courtois ruptured a left-knee ligament in August, just two days before the start of the season. The 32-year-old Belgian then also ruptured the meniscus in his right knee in March, when he was close to making a comeback.
He was sidelined until the beginning of this month, when he started in a 3-0 win over Cadiz, a victory that secured Madrid's 36th Spanish league title.
Lunin was back in goal as Madrid beat Bayern Munich in the Champions League semifinals. He had saved two penalties in the decisive shootout win over Manchester City in the quarterfinals.
Lunin had earned the starting position over Kepa Arrizabalaga, the former Chelsea player who is Madrid's other reserve goalkeeper. Ancelotti said Lunin was the best goalkeeper in the world right now.
Courtois has proven experience in finals, though, having won the 2022 Champions League with Madrid, the FA Cup with Chelsea, the Europa League with Atletico Madrid, and two Copa del Rey titles (one for Madrid, one for Atletico), among several other titles.
"Both deserve to play for various reasons," Ancelotti said.
Ancelotti joked that he will wait as long as possible to announce the starting goalkeeper because otherwise the debate would be over, and "I like the debate."