Chelsea are doing well currently; we all know that, and if we should follow how Manchester United performance was going before sacking Erik Ten Hag, then I would say we should be expecting Chelsea to beat Manchester United for sure. But since they have a new manager now, we don’t know what type of strategy he will come with,
so we can’t conclude for now till then. But you are right with what you said; if they later fail to do as expected, the criticism on Erik Ten Hag will be in their head again. But let's wait and see what will happen when they meet with Chelsea, but United have a lot of hard work to do to meet up the points.
Chelsea are currently in good form in the Premier League while Manchester United have been very poor this season, they have only recently started to look like a winning team. This match is not an easy one to predict, whether Manchester United changes their coach or not, I believe they always put in their best whenever they play Chelsea, regardless of the coach or tactics. I’m confident that this match will be the start of a new and better era for Manchester United.
Chelsea are the main guys in that fixture, the game play revolves around them if they decide to keep same performance like every other tough fixtures they had this season then a win over United shouldn't be a big deal. Manchester United are trying to uplift their performance, a new coach does not certify their possibility of winning the game, moreover the worst performance they have been on was basically coming from the players themselves due to how many goal opportunities they missed.
Not tough to decide on the outcome, Chelsea are having it but with some benefits of doubt i wouldn't go all in for Chelsea but the odds are likely in favor of Maresca's team delivering an impressive performance.