Heraldo de Madrid - Isak set for Liverpool debut in Atletico Madrid Champions League clash

Isak joined the Premier League champions in a British-record £125 million ($169 million) move from Newcastle on transfer deadline day.

The 25-year-old did not feature in Sunday's 1-0 win at Burnley -- Liverpool's first match since his blockbuster transfer -- because he is still short of full fitness after missing much of the pre-season.

Isak had trained alone in a bid to force through his switch, leaving him in need of extra work to get up to speed.

"Definitely a chance because he's in the squad, so then there's a chance to play. I would usually say 99.9 percent sure, but I can say 100 percent sure he will not play 90 minutes," Slot told reporters on Tuesday.

Asked if there was a chance of Isak starting at Anfield, Slot said: "The only thing we're sure of is he will not play 90.

"He's part of the squad, so it's already a Champions League game to look forward to, but if people look forward to his playing time, that could mean that could happen tomorrow as well."

Isak's goals helped Newcastle end their 56-year trophy drought when they defeated Liverpool in the League Cup final last season, while the Magpies also qualified for the Champions League thanks in large part to the Swede's prolific form.

But his only appearance this season came for Sweden in an 18-minute substitute cameo in a 2-0 defeat against Kosovo on September 8.

Slot said getting fit was the striker's biggest challenge.

"He doesn't have to prove to anyone that he's good enough to play in the Premier League, because that's what he's proven already at Newcastle," said the Dutchman.

"So the main challenge he has is to become so fit that he's first of all ready to do what he did last season."

- 'Above expectations' -

The spotlight will be firmly fixed on Isak, which could be a blessing for Liverpool playmaker Florian Wirtz.

Prior to Isak's arrival, the German was briefly Liverpool's club-record signing after his summer move from Bayer Leverkusen for an initial £100 million.

Wirtz has struggled to make an impact, leading to suggestions the hefty price tag is weighing on him.

Slot was quick to defend the 22-year-old, saying: "There's so much focus on our new signings. He's been part of a team that is on top of the league, that won four games.

"Yes, he hasn't scored four goals or 12 assists in the first four games, but for me that's down to the quality we've faced, and he's part of a team that's number one in the league at the moment."

Liverpool's off-season was dominated by the death of forward Diogo Jota in a car crash in July, which Slot acknowledged had had a profound impact on the club.

Yet despite that trauma and a significant rebuild at the cost of nearly £450 million ($614 million), they are top of the Premier League with four wins in four games.

"It's only a compliment that people tell everyone that we've spent so much because that tells you the players we've brought in are seen as very good players," Slot said.

He added that the team were performing "far above" his expectations.

"For us to be on 12 points now is so much more than I expected, especially after we've had so many changes in the group as well," he said.

H.Roldan--HdM