Eden Hazard scored his first Real Madrid goal in eight months on Thursday as La Liga's leaders staged a dramatic comeback with 10 men to scrape past Elche in the Copa del Rey.
Real Madrid's Luka Modric and Marcelo have tested positive for COVID-19 and will miss Sunday's La Liga match.
Marcelo has played 18 matches for Real Madrid this season, of which 10 have come in La Liga.
Brazil are going through their paces in Sochi ahead of their Group E engagements.
Neymar's returning form will be a key factor for the team, which lost influential right-back Dani Alves to a knee injury last week.
Real Madrid moved a step closer to a third straight Champions League title after substitute Marco Asensio hit the winner in a 2-1 semi-final, first-leg victory at Bayern Munich on Wednesday.
Luka Modric has a thigh injury, meaning he is set to sit out Wednesday's rearranged La Liga game at Leganes