I think Liverpool has everything to beat Man United. They performed well in EPL matches lately, they also will play at home in the upcoming match. They are unbeatable in the last 5 matches, meanwhile Man United always performed very unstable. Moreover, there are too many problem with Man United lately, it may bother their focus in playing. So, there is no reason that the match against Man United will end with a draw. I'm very sure that Liverpool will get full points in the upcoming match. I even doubt that Arsenal can easily win against Brighton. This team sometimes becomes the obstacle of the top teams in EPL. So, Arsenal can't underestimate Brighton although Arsenal is superior against them.
Liverpool is more powerful than Manchester United right now and I am sure if the both team should meet, Liverpool will definitely beat Manchester United down the table so they are remain at the top of the table standing while Manchester United on the other hand is trying to gain it's feet on the table.
Whereas Arsenal is currently working hard to overtake Liverpool in the table to retain their position once again. That alone will push them further in the next March so they can win more goals against Brighton but if they win, it won't stop Liverpool to go ahead of them especially when Liverpool always win in their subsequent matches too.