Chelsea have home advantage and manchester united will play well with the absence of Ronaldo, like their previous game, which they won 2 nil against Tottenham Hotspur, it was without Ronaldo and was an easy game for devil's.
Im not sure if this is relevant but Ronaldo hasnt been starting for a while on EPL games and Rashford has been getting that spotlight on most EPL games as starter so it doesnt really matter at this point if Ronaldo play or not.
Aside from that, imagine being Ronaldo though. You are a top player and you think you are bigger than the club but then you got schooled by Ten Hag because your attitude sucks. You are paid by the club but then you refused to go on as a late substitute and left early on the match against Tottenham. I doubt any other coach would be able to do that to a top player like Ronaldo