even with that i still doubt chelsea will win
Chelsea always feels so difficult to beat United even when their opponent in the shitty season (h2h). However, they may get more motivation to keep UCL spot in their hand, and must get three points from MU. Three points from MU is very very very important to keep up their chance to qualify for UCL next season.
The odds literally says almost zero chance for MU to be up in this game, but often saw MU performed differently in the important game. They have to smash MU, or they will miss UCL.
Chelsea will win Manchester United so that they can remain in the top 5 position for them to qualify for qualify for the Champions League whereas Manchester United are more interested in their Europa League final against Tottenham since that is the only way they can make it to the Champions League games next season. Besides this analysis, Chelsea is more trustworthy in the Premier League than Manchester United so even if United didn't have an Europa League final, Chelsea will still have the upper hand. I don't know why you think that Chelsea finds it difficult to beat United because the last time i checked the head to head of both teams, Chelsea won 24 times why Manchester United won 22 times so it shows that Chelsea dominates more when they meet United.
Based on historical data Chelsea won Manchester united when they are on their home ground more than once and just like you stated Chelsea would do what they can to either maintain their Position or surpass Manchester city, this means that they need at least 3 points, I'm not entirely sure of this but Chelsea is the better side here...both teams have been rivals in the past but currently they are not on the same level when it comes to strength.