Slot had previously questioned Nunez’s work rate following his costly miss against Aston Villa, opting to bench him against Manchester City.
However, the Uruguayan returned in Wednesday’s win over Newcastle, and Van Dijk reinforced the need for players to give maximum effort at all times.
Van Dijk stated: "That is the bare minimum that has been asked of the whole squad from day one.
“But that is the bare minimum anyway for playing for Liverpool. It was more down to him and it is still down to him, but I think he showed a great reaction today in his work rate and coming on. That should be the minimum and he knows it.
"Everyone has a big role to play. I mentioned it last week after Aston Villa. We are all in this together and we need everyone. He is a big part of the team as well and when he comes on, he has to make a positive impact. We have to keep that going."