In the first meeting this season, Man United successfully destroyed Southampton 3-0 at their home base, this time I am very sure that Man United will again win over Southampton because they are in high spirits after successfully eliminating Arsenal in the FA Cup, plus this game will be played at Old Trafford. In fact, Man United is also not in its best form in the EPL, they have never won in the last four matches, but Southampton's weakness is an advantage for Man United to improve its position in the standings.
Apart from Manchester United being on a high spirit they would have won Southampton on a normal time because the deference between worst and worster is big because Manchester United is worst while Southampton is worster than them, so they will get another beating again from Manchester United, however I think is good that Southampton may not be coming to the premier League next season because their weight are too light to play on this premier League, so definitely they would see their match on the championship if is were their fate take them to.