The club announced on Tuesday Rudiger had successful surgery on his left knee to repair the meniscus and is expected to return "early next season."
The news is a big blow for Chelsea, who are still competing for the UEFA Europa League and a spot in the Premier League's top four. Rudiger has only recently returned from a knee issue but suffered a fresh injury to his meniscus during the 1-1 draw with United.
The Chelsea man posted the following message on social media following the game:
This season, the 26-year-old has established himself as a key player under manager Maurizio Sarri, with the Italian opting to pair Rudiger with David Luiz in his first-choice centre-back duo.
At the start of the campaign in particular, the German was excellent. Not only did he use his physicality and dynamism to great effect, Rudiger showcased his defensive instincts and composure on the ball.
In the second half of the season his performances have been a little more erratic, especially in away matches when the Blues have struggled to keep the opposition out. Even so, Bleacher Report's Sam Tighe included him in his alternative Team of the Year:
With Rudiger sitting out the rest of the campaign, there is likely to be a chance for Andreas Christensen to make his case for a more frequent starting spot.
Last season, the Denmark international impressed under Antonio Conte, although his stock has fallen under Sarri in 2018-19. Miguel Delaney of The Independent commented on his struggles when he replaced Rudiger in the recent loss to Liverpool:
Chelsea are in a strong position to qualify for next season's UEFA Champions League. They sit in fourth spot in the table and know wins against Watford and Leicester City in their last two games will be enough for them to finish ahead of Arsenal and United.
They are also in action in the Europa League on Thursday, when they face Eintracht Frankfurt in the first leg of their semi-final showdown.