Liverpool £141m partnership has been kept apart and now it must deliver for Slot

Similar to last season, Isak must now shoulder the burden of helping his team scramble to secure a Champions League qualification berth during the closing six games of the campaign.

For a player who moved to Anfield with sights on far more lofty ambitions, it is a significant downgrade in target and ambition given the pain and furore he had to traverse before realising his record-breaking transfer.

That, though, has been the way for Liverpool under Arne Slot this season, their hopes of Champions League glory going the same way as those of defending the Premier League title and claiming the FA Cup and League Cup when they were dumped out by holders Paris Saint-Germain in the quarter-final stage on Tuesday.

The defeat was compounded by the suspected Achilles injury suffered by Hugo Ekitike that, if reports from the striker's native France are confirmed by Liverpool, could mean the 23-year-old doesn't feature again until 2027.

Slot at the very least expects Ekitike to be missing for the rest of this season. And with Liverpool shorn of their top scorer, the onus will now be on Isak to finally begin delivering at a time when the Reds need it most as they look to hold on to the top-five berth that will earn Champions League qualification for next season.

Isak, of course, has himself been no stranger to the treatment room this term, having arrived not fully fit and then suffering a groin problem before breaking his leg at Tottenham Hotspur shortly before Christmas.

Tuesday represented a surprise first start since that injury, the Sweden international playing the opening 45 minutes. But while Slot was heavily criticised by some for that selection, in hindsight it may ultimately prove of benefit in the short-term.

Certainly, Isak needs the exposure. He touched the ball only five times during his outing, although he had one effort saved and was flagged offside when seeing another shot repelled. By contrast, Ekitike had 13 touches before suffering his injury in the 27th minute.

While perhaps not quite as much off the pace as some of his agenda-driven detractors would claim, it's obvious Isak, as well as building up his match sharpness, is continuing to work on his understanding with team-mates, hardly surprising given he is yet to play a full match for Liverpool and teenager Rio Ngumoha has played almost as many minutes for the club.

The worry for the Reds is Isak has rarely looked on the same wavelength as many of his colleagues when available. There were fleeting glimpses at home to Atletico Madrid in the Champions League in September and a better showing at West Ham United in November.

And it was in the process of scoring his third and most recent Liverpool goal at Tottenham Hotspur the following month that he sustained his serious leg injury when caught by Spurs defender Micky van de Ven. But that has been about it.

That goal against the Londoners came when despatching a throughball from Florian Wirtz, Liverpool's other big-money signing of the summer who Slot and sporting director Richard Hughes envisaged forming a strong partnership with the striker.

Instead, the duo have spent just 481 minutes on the pitch together - the equivalent of less than five-and-a-half matches - with that strike the only one for which they have directly combined.

If Isak has no option but to ramp his contribution, the same can be said of the £116m Wirtz during the closing weeks of the campaign. After an impressive winter, the Germany international hasn't been the same since the back injury that ruled him out for three games at the end of February.

He frustrated against Paris Saint-Germain, seeing a fair chunk of possession - only six players had more from either side, while no player completed more key passes - but too often promising more than was actually delivered.

A first Merseyside derby at Everton's Hill Dickinson Stadium on Sunday will therefore be the ideal setting to determine the hunger in Wirtz and potentially Isak, although Cody Gakpo, decent in the second half against PSG, is a more likely starter down the centre of attack.

Beyond doubt, though, is that if Liverpool are to salvage the bare minimum of a Champions League berth from a hugely disappointing season, their big-money duo are going to have to start delivering. And quickly.