It's a headache that has been nagging away at Jurgen Klopp for too long than the Liverpool manager would care to remember.
And time is now almost up for the Reds to find a solution, even if it ultimately serves only as a sticking plaster until the issue is properly addressed.
With a week to go before the start of the Premier League season, Liverpool face the prospect of heading into the opener at Chelsea without a proven defensive midfielder.
Of course, with the transfer market remaining open until the end of the month, there remains sufficient time for at least one new number six to be brought into the club, with Southampton's Romeo Lavia the preferred target and contact made over Fluminense's Brazil international Andre.
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But with a trip to Newcastle United and a home clash against Aston Villa all scheduled before the international break in early September, Klopp's side can ill afford to compromise their hopes of maintaining the strong momentum they gained towards the end of last season as they look to regain their place in the top four.
The answer, then, will probably have to come from within. The game is too soon for 18-year-old Stefan Bajcetic after more than four months on the sidelines, with Thiago Alcantara also not in consideration. And while none are ideal, Klopp has some options for when his team steps out at Stamford Bridge next Sunday.
The youthful choice
Liverpool began pre-season with two games in Germany, in which Trent Alexander-Arnold started in the number six role and Conor Bradley, having hugely impressed on loan at
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