The Reds battled to a 2-1 win with a much-changed line-up on the night.
Slot, who watched the game from the stands due to suspension, said: "It would be normal if I play with all the regular starters that we have a better team than we have tonight otherwise I make every week the wrong decision.
"Maybe it's a possibility! We also trust these players because we know how much quality they have. So, that's the first reason to play these players. We have a lot of confidence in them as well.
"Second of all, it's not about the result on Sunday, it's more for the long-term fitness of the players that we made the decision that the ones who have played so many minutes to give them a bit of rest during this week because the schedule is going to be intense again in the upcoming weeks.
"For the ones who have played a lot, only 45 or 60 minutes, and the ones who haven't played a lot play 90. That's what we did, and it was good for us that it was enough to win it."