Arne Slot makes bold Isak prediction as he battles to get striker up to speed

Arne Slot has warned he will have to sacrifice the claims of other forwards for Alexander Isak after admitting his £125million striker is still lacking fitness.

The Sweden international has yet to complete 90 minutes for Liverpool since his acrimonious British record move from Newcastle; he hasn't played for his club since suffering a groin issue during a 5-1 win against Eintracht Frankfurt on October 22.

Though he had a 28-minute run out for his country against Switzerland last Saturday, Isak is behind his club colleagues in terms of physical capacity, so much so that Slot spoke with Liverpool's strength-and-conditioning department on Friday to see what steps they could take to change the situation.

It has left Liverpool's head coach aware that, with a run of seven games in 22 days on the horizon, he is going to have no other option but to start Isak, to give him the football he requires, even if it comes at the expense of team-mates who are in a better condition.

'We can improve as a team and we will improve definitely as individuals because players will be adapted to the league much better,' said Slot. 'With Alex, it will still take a bit of time but he will end up being the player he was at Newcastle if we get him fit.

'I do know that 100 per cent fit Alexander Isak is a big, big, big plus for this team. But for him to get there, he might need to have minutes where you could argue that another player might be further ahead of him in terms of match fitness.'

There is no question this is a challenging situation for Slot, who will be without £116m midfielder Florian Wirtz against Nottingham Forest and, in all likelihood, PSV Eindhoven after he returned from Germany's World Cup qualifiers with muscle damage.

Isak and Wirtz were signed to give the league champions a new attacking dimension and the near quarter-billion investment came with an assumption that Liverpool would be free scorers but, so far, the only goal between them was Isak's against Southampton in the Carabao Cup on September 23.

During that game, Isak was told he had to do extra running at half-time – it had been pre-arranged he was only going to play 45 minutes – to build up his stamina and Slot explained he is looking at ways to build up his No 9's schedule.

'People asked why did we do this (against Southampton) but it is to build him up,' said Slot. 'If he plays a game, he has to do more accelerations and decelerations. If he does some running, you can give him a bigger tank.

'This morning, I had a conversation with the performance staff, "what is the best way for him – not for Liverpool – to get him as fast as we can to that 100 per cent?" I always have to find the balance between what is the best for him as an individual and for us as a team.'

Whether Isak starts against Nottingham Forest, or is saved for the Champions League fixture with PSV Eindhoven, Slot remains convinced – and spoke with conviction – that it is only a matter of time before people see the ability that won him so many admirers in the North East.

Clearly there is still a significant hangover from a disrupted summer, when he effectively went on strike at Newcastle to secure a move away, and Slot has pointed out that a number of his squad have been in a similar situation – all of which has had an impact on performances.

Asked why he was so sure about why crowds will see the Isak of Newcastle, Slot replied: 'Or how he was at Sociedad or all the other clubs he was at – he just needs to become fit. That is the challenge.

'It is underestimated, so much, that if you bring a player in on September 1, when the league is already three weeks in. He didn't do a lot of high intensity runs. So we had to build him up, which is normal, if you have been training on your own. You cannot compare this to a team session.

'If you then get an injury, you are thrown back again. So give him time. The problem is, I play a player – and I have done this with others – who is not 100 per cent of their usual match fitness. But then I cannot play friendlies. You can do that in pre-season because you don't care about the results.

'But Alex and (Alexis) Mac Allister are the best examples of that. Conor Bradley got injured in pre-season. Ah, I could go on and on. That is the challenge with him. I can see in training sessions, if he is fully rested, then you can see his quality. He is an incredible player.'