The Portugal international has been suffering from 'flu-like symptoms and, therefore, cannot feature in our first game of the penultimate month of the season.
Our no.7 hit a hat-trick in his last Premier League outing, against Tottenham, and helped Portugal qualify for the World Cup finals during the international break, appearing in wins against Turkey and North Macedonia.
Ronaldo was unable to train on Friday with the rest of the squad and, in the morning, he was still feeling too unwell to feature against the Foxes.
Bruno Fernandes could take his place in attack as a 'false nine', after being included along fast wide players Anthony Elanga and Jadon Sancho.