I am still optimistic that in a situation as complicated as this Madrid should be able to win 3 points over Celta Vigo. Although the stakes are the players fatigue. After all this has happened more than once, so Madrid's players are professional and used to a tight schedule. It is not too worrying because Ancelotti also realizes that this 3 point opportunity must be utilized well so that the gap from Barcelona remains small. Or maybe Ancelotti gives Arda Guler and Endrick to appear in the starting eleven. Mbappe and Rodrygo can handle the front line and hope Vini will not miss the match against Celta Vigo.
For now, Vinicius is still in recovery condition although he could appear when Real Madrid faces Celta Vigo because the recovery deadline for Vinicius is only two days from now. But there will also be a possibility for Ancelotti to play Arda Guler and Endrick in the match because both are still quite fit and several other players also still need rest for other more important matches. I also have no doubts about Real Madrid's ability to get three points at Celta Vigo's home ground because it is true as you said that Real Madrid need to keep the points gap close to Barcelona at times like this.
Madrid so far is a team that has a good squad depth, even though they are currently being hit by a storm of injuries but I think Carlo Ancelotti is most likely to rotate and provide opportunities for young players, the match against Celta Vigo should be an easy match for them to remember the head to head of the two teams so far, but remembering the inconsistency and also the number of Madrid players who are currently injured I think Madrid will definitely get a tough challenge in the match, against Celta Vigo will be a very crucial match to maintain the distance with Barcelona in the current La Liga standings, so far Vinicius may be doubtful to play after the injury he got, but Mbappe and Rodrygo look like they will be Madrid mainstays in the match and they still have a strong attacking in front line.