Slot also stated Fede Chiesa will feature at St Mary's tomorrow.
Liverpool meet Saints after their dismissal of manager Russell Martin and Slot said, "In my opinion it is a pity. These things happen. Russell Martin has done so well last season for Southampton. This season again (his side) played good football. We experienced this when we had such a tough day over there. We only beat them 3-2.
"So you always feel sorry if managers don't get the chance to continue. Especially in these two situations because for me they were managers who had a good idea of how they wanted to play with their team. Unfortunately, they weren't able to get enough points - then managers get sacked.
"It's difficult what we can expect in terms of formation, in terms of personnel but what we do know is that we have to play an away game against Southampton, against XI players."
To be alive in all competitions, Slot also said: "To a certain extent yes because I think that is normal for Liverpool to be fighting for every trophy and to be for a long time in every cup to go all the way.
"This happened last season when this club won this competition. So I am not surprised with the quality we have that we are competing at this moment for these three trophies, and the fourth one (the FA Cup) is starting in January.
"It is a challenge because we have a lot of great competition here in other teams as well. In the League Cup, if you look at the other teams that are still in it, none of the teams that are in are going to be an easy road to the final."