Away from locally trained players, clubs are allowed to name a maximum of 17 overseas players on List A as part of their 25-man squad, along with as many qualifying Under-21s players on List B as they wish. The Reds currently boast 16 overseas players over the age of 21.

However, despite being classified as Under-21s players when it comes to Premier League rules, neither Gravenberch or highly-rated starlet Ben Doak are eligible for a place on List B. This is because, ‘a player may be registered on List B if he is born on, or after, 1 January 2002 and has been eligible to play for the club concerned for any uninterrupted period of two years since his 15th birthday by the time he is registered with UEFA – or for a total of three consecutive years with a maximum of one loan period to a club from the same association for a period not longer than one year.’

With Doak joining the club from Celtic last summer, and Gravenberch only just signing for the Reds, neither have clocked up the required ‘uninterrupted period of two years’ at Anfield. Therefore, they are vying for that final overseas berth in the senior 25-man squad.

If in the Champions League, it would be an easy decision for Klopp. Select his new £40m signing in Gravenberch, with Doak having to make do with UEFA Youth League action for another season instead. But with the 17-year-old impressing throughout pre-season, following on from an eye-catching first season on Merseyside, the Europa League was seen as a great opportunity to hand the winger first-team minutes.

After all, Klopp is expected to initially rotate his side in Europe’s secondary competition, while there is no Europa League-equivalent to the UEFA Youth League for the club’s younger players to participate in.

So while the likes of Bobby Clark, Conor Bradley and Jarell Quansah can be named on List B, joining senior players Harvey Elliott, Stefan Bajcetic, and still feature in the Europa League, Doak won’t be afforded the same opportunity if he is the unfortunate player to make way following Gravenberch’s arrival.

However, there is one UEFA rule which could enable Klopp to include both players in his 25-man Europa League squad at the expense of one of their senior team-mates.

Clubs must include at least two goalkeepers on List A and at least three in total (List A and List B combined). Liverpool currently boast the services of four goalkeepers who would need to be registered on List A (Alisson, Adrian, Kelleher and Jaros), along with the likes of Marcelo Pitaluga on List B.

Now Kelleher and Jaros both contribute to the Reds’ quota of locally trained players. While the Irishman is certain to be selected, and perhaps likely to start ahead of Alisson in the Europa League group-stages if Klopp rotates his squad, if Jaros is not selected then Liverpool’s squad reduces further to 22 players.

As a result, Klopp could leave Adrian out of his Europa League squad and utilise Jaros as his third-choice goalkeeper. Alternatively, he could leave both players out and call upon Pitaluga’s services from List B as back-up instead.

In the latter scenario, the Reds would be protected should they lose the services of either Alisson or Kelleher. UEFA rules state that if a club cannot count on the services of at least two goalkeepers registered on List A because of long-term injury or illness (i.e. one that lasts 30 days), a club can temporarily replace him at any time during the season.

Consequently, if Alisson and Kelleher were Liverpool’s only two goalkeepers on List A for the Europa League group-stages, if either was unavailable, it would be possible for Klopp to temporarily replace them with Adrian or Jaros at a later date.

In truth, supporters would favour such a low-risk gamble if it ensured that all senior overseas outfield players are named in the Reds’ squad, including Gravenberch, and that Doak can still be afforded game-time in this season’s Europa League. But whether Klopp wishes to make such a decision at the expense of a back-up goalkeeper remains to be seen.

Possible Liverpool squad for Europa League group-stages (CT means club-trained)

Goalkeepers: Alisson, Caoimhin Kelleher (CT), Vitezslav Jaros (CT).

Defenders: Joe Gomez (CT), Virgil van Dijk, Ibrahima Konate, Kostas Tsimikas, Andy Robertson, Joel Matip, Trent Alexander-Arnold (CT).

Midfielders: Wataru Endo, Thiago Alcantara, Dominik Szoboszlai, Alexis Mac Allister, Curtis Jones (CT), Ryan Gravenberch.