Wirtz, 22, was set to start for Slot’s side in their trip to The City Ground put picked up an injury in the pre-match warm-up.
Curtis Jones took his place as Liverpool snatched a dramatic late win thanks to a 97th minute goal from Alexis Mac Allister.
Speaking to reporters after the game, Slot revealed that Wirtz’s injury wasn’t “serious” and expects him to be available next week.
Slot said: "We don't think it is very serious, but he felt his back too much during the warm-up to start.
"He wasn't able to be 100 per cent or even close to 100 per cent. I think after being in this league for six, seven or eight months, he now understands no matter how good you are on the ball, you need to be 100 per cent at this level.
"So, we decided not to play him. We hope and expect he will be able to be with us again next week but you never know how things work out."