I'd say if Bellingham, Mbappe, Vini and Rodrygo don't suffer injuries, Madrid's performance will be stable. These 4 are the most important players in Madrid's squad at the moment. If the bonding between these four players is strong, Madrid's overall performance will be even stronger.
These 4 players are very important to Real Madrid but I don't think they're the only ones you should b praying to avoid an injury. The midfield and defence don't have enough depth too. An injury to Valverde or Camavinga can be a problem. In defence, Madrid have only Militao and Rudiger currently fit for centre-back positions, if an injury is to happen to any of them then there will be trouble.
So even if Bellingham, Mbappe, Vinicius and Rodrygo don't get injured, the team might be in serious trouble if more midfielders and defenders get injured.
The success of Madrid this season might rely solely on the chemistry between their front line. The wings need to be in sync because Madrid will rely on them to create chances and score goals since the midfield can't create chances.