You're right, southempton always bring their best performance more especially when they are playing with bigger teams. on the second thought southempton is in the bottom of the table just about going for relegation this season, with this I think the match is going to be a little bit tough for liverpool. As liverpool will also want to reserve those thier key players ahead of thier upcoming match against psg in the champions league, I think that is thier major concern for now. But regardless to that I still have this strong believe that liverpool will gain victory over southempton.
In this match Liverpool is very advantaged, especially since they are facing a low-ranking team in the standings which will pave the way for Salah et al to get 3 points in the 29th match. Southampton will be overwhelmed in this match because they are no longer enthusiastic about improving their ranking because they are already quite far behind from a safe position in the standings.
They may now be cruelly interested in bringing down Liverpool's points in the table, as relegation awaits them, the saints would desire a memorable win. However, the favorite side perhaps will perform at high levels, but must select the best players for the match. It's an interesting game to look up to, hopefully the reds comes out victorious.