Gumshield-wearing Wataru Endo is Liverpool’s unlikely key cog that unleashed Alexis Mac Allister

Wataru Endo has become Liverpool defenders’ ultimate protective shield. Or perhaps gumshield would be more appropriate.

The Japan international looks like he is preparing for 12 rounds in the boxing ring rather than a football match, a quirky charm that has endeared him to the Kop during a brilliant run.

“When I was in Germany I met a Japanese dentist; he told me it’s a good mouthpiece, it makes something different about performance,” Endo told Sky Sports recently.

“Now I just wear it to protect my teeth and also it looks like a fighter, so when I go into the pitch I just put the mouthpiece on and it’s like game mode.”

The 31-year-old, rested against Sheffield United on Thursday night, should be back for the scrap with Manchester United this weekend as another emblem of the contrasting recruitment choices of clubs which have gone in different directions.

It seems a lifetime ago since United played Liverpool with their world-renowned and highly-decorated Brazilian midfielder Casemiro regarded in some quarters as the difference between Erik ten Hag leading his club back into the top four while Jurgen Klopp prepared for Champions League exile as time caught up with Fabinho, Jordan Henderson and James Milner.

Casemiro cost £70 million, and it is unlikely he accepted a salary cut from the excess of £200,000 a week he was earning at Real Madrid.

Endo was unfashionably cheaper at current market rates, £18 million on a contract that is most likely less than half of his United counterpart. Both are in their early 30s, but while Endo’s performances this season have defied age and re-energised Liverpool’s midfield – Klopp predicting his successor ‘will want to give him another long-term contract’ – there is a lingering feeling Casemiro’s best is behind him, the occasional reminder of his class not enough to silence those who think him representative of the excesses of an on-the-hoof Old Trafford transfer strategy.

If Alexis Mac Allister was the perfect farewell gift of Liverpool’s ex-sporting director Julian Ward, Endo was Jörg Schmadtke’s eureka moment.

Schmadtke was only employed to cover two transfer windows, and his arrival was greeted with some suspicion during what history will record as Michael Edwards’ two-year Anfield sabbatical.

But his knowledge of the Bundesliga ensured he and Klopp recognised what few other elite clubs did when watching Endo in Stuttgart’s midfield for the past three years.

As Klopp has since acknowledged, there was luck involved in Liverpool moving for the Japan skipper as they spent most of last summer trying to lure Romeo Lavia, before offering a startling £111 million for Moises Caicedo – sliding doors moments in Klopp’s farewell campaign.

In terms of his age profile, Endo was an atypical signing, the move portrayed as astute from those who believed Klopp could do no wrong, and a desperate, emergency response by others who wondered if the manager and Schmadtke were veering from the Anfield recruitment policy which has yielded such success. The fact so many clubs were looking for a No 6 – including Bayern Munich who had regularly faced Endo in the Bundesliga – served only to increase cynicism about how good he might be.

“The owners really want a 20-year-old who has played 200 games,” Klopp admitted upon completing the deal. “I know people are asking why no-one signed him [Endo] before.”

Given the initial cynicism, it is no coincidence that Klopp welcomed Endo with the most effusive praise ever bestowed upon one of his signings, revealing an assortment of congratulatory text messages from his German friends for a ‘genius’ move.

“He jumps through a ceiling, is really good in general defensive challenges, tactically really smart, closing down the right players, good footballer on top of that, good heart, desire, a really good package,” said Klopp last August.

“When you see him running around now there is no chance anyone would give him 30 years, he doesn’t look old enough to drive a car, on the pitch he looks like a monster.”

Despite an inauspicious start, Klopp has been spectacularly vindicated.

But while the energy, tenacity and terrier-like retrieval of possession are obvious stand-out qualities, it is the influence on those around Endo that has had the most profound impact on Liverpool’s season, especially his midfield partner Mac Allister.

As Endo was adapting to Klopp’s system and Mac Allister was the defensive No 6, the Argentine registered no goals, one assist and five shots in his first 11 Premier League games.

Since Endo established himself – he has missed only four of the last 19 league games (three because of Asia Cup duty) – Mac Allister has four goals, four assists and 24 shots, his creative talent unleashed in a perfectly-balanced midfield.

Endo is a shy, low-maintenance presence around Liverpool’s training ground, content that others are enjoying more of the limelight in the title push.

He cannot escape the fact that he and Mac Allister are in the midst of an almighty fight every week for the status of Liverpool’s bargain of the season. No wonder Endo keeps wearing that gumshield.