Rashford impressed at the Etihad as United took a 2-0 lead against their rivals.
Bruno Fernandes netted a penalty after Gabriel Jesus fouled Anthony Martial in the first minute of the match.
Luke Shaw doubled the lead early in the second half with a fine individual effort which gave Ederson no chance at all.
Rashford went into the match with a shoulder knock and it is believed the England international may need surgery at some stage on the persistent problem.
Man Utd wages: Pogba and De Gea ahead of Cavani and Fernandes as salaries emerge
We’ll be bringing you the very latest updates, pictures and video on this breaking news story.
For the latest news and breaking news visit: express.co.uk/sport/football
Stay up to date with all the big headlines, pictures, analysis, opinion and video on the stories that matter to you.
Follow us on Twitter @DExpress_Sport – the official Daily Express & Express.co.uk Twitter account – providing real news in real time.
We’re also on Facebook @DailyExpressSport – offering your must-see news, features, videos and pictures throughout the day to like, comment and share from the Daily Express, Sunday Express and Express.co.uk.