Nunez was called out by manager Arne Slot last week for his lack of work off the ball in recent games.
However, Van Dijk has seen an improvement in Nunez's commitment since then.
“That’s the bare minimum that’s been asked from us from day one, but that’s the bare minimum anyway for playing for Liverpool,” said Van Dijk. “That was down to him, and it’s still down to him, and he showed a great reaction in his work rate.
“That should be the minimum, and he knows it, so you have to keep going. Everyone has a big role to play, that’s the thing. We’re all in this together, we need everyone and he’s a big part of our team as well.
“When he comes on, he has to make a positive impact. He, and the rest of the boys who came on against Newcastle, made a big impact. That’s what we need so we just have to keep that going.”