The Sweden striker is "not too bad" but is a "question mark" after sustaining a groin injury in Wednesday's 5-1 Champions League victory over Eintracht Frankfurt. Midfielder Ryan Gravenberch, who missed the Frankfurt match with an ankle issue, is also a doubt.
The Reds are third in the table after losses to Crystal Palace, Chelsea and Manchester United, and Slot said his side must adapt to a changing tactical landscape, pointing to a shift in how opponents are approaching games against them.
"I try to tell (the players) that the main, main, main, main difference between this season and last season is the playing styles we face," Slot told reporters on Friday. "We had to defend 178 long balls in (the first) seven games, and then the United game, we had to defend 59 long balls. That's different than the first half of last season."
Slot believes the key to breaking down these low-block, direct teams lies in moments of individual brilliance or set pieces.
"The way to unlock it is a moment of magic, which we had in the first half of (last) season, a lot with Mo (Salah), or a set piece, which we had at Frankfurt as well," he said. "Two set pieces (goals from corners) unlocked the game for us."
He also defended his comments about United's tactics, saying they were meant as a compliment.
"When I tried to explain this in the media, it was actually more of a compliment for the other manager (Ruben Amorim), that he found the right answer to our playing style," Slot said. "But I think if I'm correct, that wasn't how people looked at it."
Jeremie Frimpong, who reaggravated a hamstring injury on Wednesday, will be out for the next couple games at least, Slot said, while goalkeeper Alisson Becker remains out.