As Liverpool get set for a crunch tie with Manchester United on the back of the international break, there is one position they won't have many worries about when preparing for the trip to Old Trafford.

Despite the fact Jürgen Klopp lost his £65m ($79.5m) goalkeeper Alisson Becker to a calf injury on the opening day win over Norwich City, new recruit Adrián has worked tirelessly to settle into the team — contributing to the winning Premier League run which now leaves his team eight points clear at the top.

Liverpool's goalkeeping department has changed dramatically in recent years, with Klopp inheriting the likes of Simon Mignolet, Brad Jones, Adam Bogdan and Danny Ward.

All have now left the club, with Lloris Karius, Alisson, Adrián and Andy Lonergan all brought in to replace them with varying hopes and expectations. Caoimhin Kelleher has also made inroads to the first-team setup in recent months.

The one consistent throughout that turnover has been goalkeeper coach John Achterberg, a figure who has been polarised by many supporters throughout his time at Anfield after being hired by Rafael Benítez in 2009.

During Brendan Rodgers' reign in particular, there were many who would entertain conspiracies about the role of the Dutch goalkeeper coach, strangely lamenting him for not being progressive and going further to reference his personal appearance as somebody directly responsible for the team's defensive woes.

When Klopp came to Liverpool in 2015, many expected Achterberg to be one of the first to be relieved of his duties, with some even checking the employment status of Xavi Valero, Benítez's goalkeeper coach, as the man to rescue the Reds between the posts.

This summed up many attitudes towards Achterberg. The concept that there was rafts of better qualified and pedigreed coaches for the role across Europe was seen to be a given because he had played for Tranmere Rovers as a player, therefore he could not aspire to any higher level as a coach. Simply put, he wasn't good enough for Liverpool in the eyes of many.

Yet Achterberg did not budge. Instead, he got work and adapted quickly to the demands of his new coach. His insight and innovation when seeking out the latest positional trends, as well as identifying the right attributes for what was required for the ten players in front of a Liverpool number one eventually led to one of the most crucial transfers in Klopp's reign.

The experiment with Karius ultimately failed with the acceptance that there was nobody to blame, circumstances simply went against the German that resulted in the best thing being a move away from the club, in order to rebuild his career.

Although Klopp and his coaching team had made a decision to stand by Karius originally, it was Achterberg who had a huge say when it came to the opportunity to sign Alisson .

Since then, the Reds' back-line has continued to go from strength to strength. The influence of an elite goalkeeper on the team has had a profound effect on how Liverpool defend and attack, with a notably higher line being taken up the pith in order to suffocate opposition defences, something done with a trust of the Brazilian number one to sweep up any counter-attacks or saves in a one-on-one situation.

The plaudits and accolades have flooded the way of Alisson, with those who previously lay blame at the door of Achterberg now using hindsight to quip how he just needed a better quality of stopper to work with and there would be no issue — who knew?

Achterberg has the task of readying a now fit Alisson for the trip to Old Trafford. Should he be selected, Klopp will know that his coach will have fully prepared him for the threats he will face and how to overcome them. It is not a blind faith from the Liverpool boss, simply the competence he witnessed from day one at Melwood.

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His decision not to let those on the outside affect his judgement on Achterberg has proven another important one in leading the club to where they now are.