Klopp was happy with the striker's first-half for the 2-1 win.
"I couldn't see that he could sprint anymore, so that's why we had to change.
"We had a healthy, young striker on the bench. That's all. The first half was really good – really good – from Daniel. We need this player there in the centre who we can play with and if there's a ball behind the line sometimes, so that we can go there and can push up in the last line. I don't think there is an injury, it is only the situation. Nobody told me about an injury, so all is good."