As his players exit Huddersfield Town's training ground, a patchwork of green perched next to a pair of fast food outlets on a main road, David Wagner removes his trademark glasses and rubs his eyes, seemingly tired after a week where the intensity of the media spotlight has matched that of his training sessions.

But as soon as talk turns to football and last Saturday's triumph over Jose Mourinho's Manchester United, his mind starts racing again. The former Borussia Dortmund reserve team coach said the 2-1 victory was among his proudest moments in the game but, as befits a man whose ambition, drive and single-minded vision have taken this club from a post-industrial provincial town to the Premier League, it's not enough. Wagner must always look forwards.

"I think we have to be clear in our head - intelligent and smart enough to realize that this is something extraordinary and we cannot take the extraordinary for granted," he says from his modest office next to the club's gym.

"Because that's when we will make a mistake. We have no problem working on the extraordinary, day in day out but we cannot take it for granted. We have to make sure this extraordinary moment becomes ordinary for us."

The first major test of that will come quickly. On Saturday, Wagner's side face Liverpool, another of England's most storied clubs and one managed by his best friend, and the man he served as best man for, Jürgen Klopp.

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The pair played together at Mainz and worked together at Dortmund, when Klopp persuaded Wagner away from a potential career in teaching. They share a philosophy of what Wagner calls "full throttle" football - all pressing, intensity and aggression both on and off the ball.

Despite a huge gulf in resources and stature, Wagner's side are only a point behind Liverpool going in to the game. The pair are still close and despite busy schedules are in constant contact. But the Huddersfield boss rejects any notion of over-sharing.

"There is no advantage for anybody because we both know so much about each other," he explains. " I don't have any more inside knowledge about him, or about Liverpool, or about how he thinks about his players, his team than he does of me.

"If we speak about his team then we speak about everything. Individual qualities, weaknesses and strengths of individuals, opponents, the youth acadamies, the boards, what he has in Liverpool and what I have here in Huddersfield. Of course, we do still talk about other things than football..."

The fact that Wagner is laughing when he tails off from that sentence reveals something of the all-consuming energy he has brought to a club that were the first English side to win three consecutive top flight titles, before a 45-year absence from the top table that was ended last May.

Wagner guided his men to a penalty shootout win in the playoff final against Reading and, predictably enough, it was one of several Germans in the squad - Christopher Schindler - who scored the decisive spot kick.

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So far, Premier League life has been kind to Wagner and Huddersfield and it's clear he's loved in the town of about 160,000 people, where he and the vast majority of his players live.

There is a sense of togetherness at the club that Wagner often refers to, which even extends to opening the training ground canteen to the community. And he sees it as a way for a smaller side to get the edge they need to continue punching above their weight. But he's also cautious enough to take a leaf out of Rudyard Kipling's book and ensure the imposters of triumph and disaster are treated just the same.

"The most important thing is that you are not too result-driven in your day-to-day work, you have to make sure you don't get too carried away with successful or less successful periods, you have to be focused on your day-to-day work on the training pitch. Even last season we had periods without a win over 5, 6 ,7 games but the most important thing is that you are strong enough to bounce back."

Those training pitches are where Wagner does most of his best work. When he arrived at the club in November 2015 he introduced double sessions and moved training times to synchronise with match kick-off times. He says that the extra breathing space that comes with the Premier League's smaller size compared to the Championship (20 teams as opposed to 24) and an early exit in the League Cup is a particular advantage for Huddersfield.

Those extra sessions will be used to hone what Wagner often calls the "Terriers identity", a reference to Huddersfield's nickname. He says his footballing philosophy will apply as much to Liverpool as it did when they played Rotherham United in front of 10,000 in the Championship last season.

"Of course, we will have less ball possession when we play Liverpool than when we play against another team but how we like to defend, how energetic, how intense, how aggressive we like to be, this will not change. The idea and the identity will always be the same."

There's no doubt Wagner has given Huddersfield Town an unshakeable sense of self and had already performed several extraordinary feats. Twice in seven days? We'll see.