1) Rapid counter-attacks
City, as all Guardiola teams are, love to dominate the ball and keep possession for long spells of the match.
The way United can combat this is attack swiftly when the home side loses possession, just as they executed to perfection during their win at the Etihad Stadium in the Premier League earlier this season.
As mentioned before, Rashford won't be there this time so the Reds need to use the pace of Daniel James, Anthony Martial and Mason Greenwood effectively.
James is one of the quickest players in world football and if United's midfielders can put balls in behind the City full-backs, then that could prove to be very successful for the Reds.
However, it's crucial that when the Reds do win the ball back, they don't try to force the issue and panic, because that will play directly into the hands of the hosts.
City love to win the ball back quickly, so if United's players panic then it will result in either a heavy touch or a bad control and once that happens, City will be in and in a good position to strike.