Joe Gomez is able to deputise very well there but he's stretched thin at this point. Gomez is also the primary cover at right-back, while Joel Matip's injury bumped up the pecking order at centre-back, too.
Many expected Liverpool to enter the transfer market to find a new left-back but the Reds weren't interested in that. Why sign someone new who be completely redundant in a month or two?
Instead, they took advantage of Beck's form at Dundee to recall him. The youngster is in fine form, playing as one of the best left-backs in Scotland throughout 17 games. So good, in fact, that both Celtic and Rangers tried to sign him this month.
But Liverpool instead see him as important cover at left-back. He just can't be that on Sunday.
Beck is currently serving a one-game suspension in the Scottish League Cup and, as it turns out, that suspension carries over into the English FA Cup. No, it's not one that occurred to a lot of people.
And so Liverpool cannot use Beck at left-back against Arsenal. Instead, Gomez pretty much has to be the choice there - Klopp doesn't have other options available.
Instead, Beck should be completely ready to replace Gomez and face Fulham in the EFL Cup on Wednesday. That would hand out a welcome rest and more than justify the recall.
So for those looking forward to seeing what the fuss is about will have to wait a little longer - but hopefully not that much longer.