Liverpool's �125 million summer signing hasn't exactly hit the ground running at Anfield.
Whilst the team bounced back from four straight defeats with a 5-1 shellacking of Eintracht Frankfurt in the Champions League on Wednesday night, Isak was restricted to a watching brief for the second half.
Alexander Isak subbed off at half-time in Liverpool rout
At the break, having struggled to impact the game, Isak was withdrawn; the assumption being Arne Slot had made a tactical decision.
After the match, though, Isak's boss confirmed he has a fresh fitness concern regarding the striker, who has scored once - against Championship side Southampton in the League Cup - since his deadline day move from Newcastle United.
Alexander Isak had to be subbed off due to discomfort he felt in his groin," the Dutchman told reporters at full-time.
Lets hope its not too bad. It's such a difficult balance to find with a player that missed three months."
Isak went on strike at previous club Newcastle, refusing to play again for the Toon Army, alleging promises had been broken by the club's hierarchy.
As a result, he trained alone for a large portion of the summer whilst overcoming a thigh strain and had little match practice under his belt upon arriving at Anfield in early September.
His lack of minutes also caused Isak to miss the majority of Sweden's two crucial World Cup qualifiers in September, both of which they failed to win.
In FourFourTwo's view, Isak clearly hasn't settled on Merseyside the way he would have wanted and that could be due to ongoing fitness issues.
If he is not feeling 100 per cent in his body, it's unlikely he will be able to showcase his full potential in a red shirt and may require additional time to get up to speed.
Liverpool visit Brentford on Saturday evening as they return to Premier League action, before a difficult League Cup tie against Crystal Palace next Wednesday.
Slot's side have some even bigger games coming up before the November international break, hosting Real Madrid at Anfield on Tuesday, November 4, in addition to visiting Pep Guardiola's Man City on Sunday, November 9.
