Karim Benzema is progressing well in his recovery but the Real Madrid striker will only play in Saturday's derby with Atletico Madrid if there is no risk of injury.
Benzema missed Madrid's 4-1 win over Real Mallorca last weekend because of a knee injury.
It will also keep him out of Wednesday's Champions League clash with RB Leipzig, with the fixture against city rivals Atletico seen as a potential return date.
But head coach Carlo Ancelotti is unwilling to take any chances with his star striker.
He said ahead of the Leipzig clash: "He [Benzema] is progressing well, there are options. But he will only play if there is no risk of injury."
The win over Mallorca featured a clash between Vinicius Junior and visiting coach Javier Aguirre and a furious response from Marco Asensio after Ancelotti elected not to send the midfielder on from the bench.
Asked about the latter incident, Ancelotti replied: "[Asensio] cannot be considered a young man or a veteran. He is doing well and since his anger, he is training very well.
"It is what has to happen when someone gets angry, because you can train better or lower your arms. And he has opted for the first one. He has options to win tomorrow."
On Vinicius, he added: "He's fine, lively, in a good dynamic. Fully recovered from the Mallorca game. We don't talk about this, it's not something we need to talk about."
While Madrid coasted to victory over Celtic in their opening Group F game, Leipzig started their Champions League campaign with a 4-1 defeat at the hands of Shakhtar Donetsk.
Ancelotti, though, is wary of the threat posed by Leipzig, referencing their 3-0 win over Borussia Dortmund on Saturday as evidence of their quality.
"It's an important game, against a team that had problems at the beginning of the season, but a great game came together against Dortmund," said Ancelotti.
"They have quality, especially up front, technical and fast. We'll have to play a good game to try to win.
"Leipzig's attack is very dangerous, with Werner, Nkunku, Szobozslai, Forsberg - we're talking about a very dangerous team if you give them the chance to show their quality.
"I think the defensive aspect will be as important as the offensive."