Jurgen Klopp and David Wagner: Up close and personal with the Liverpool and Huddersfield bosses

Twenty-six years after meeting, Jurgen Klopp and David Wagner come face to face in the dugout for the first time in a competitive game at Anfield this weekend.

Back in 1991, two young German second division players met for the first time at Mainz 05 to start a friendship that would last till this day, although neither could imagine that one day there would be a framed picture of them together in the manager's office at Liverpool FC.

"Somebody, I do not know how it happened, put us together in a room and that was the start of a lifelong friendship," said Klopp in a Sky Sports documentary that airs on Sky Sports Premier League on Friday and is available On Demand.

Technically average, endurance average, but because of his attitude, he ran more than he usually did

"It is like family, so we understand each other as brothers and it feels like this as it is that long.

"He was not very consistent, even if he does not want to hear it! A big talent, but not every day! He was very a young player when he came from Eintracht Frankfurt to Mainz, a very skilled boy, very quick, a good striker."

Wagner, meanwhile, remembers Klopp as "quick, strong in the air with a great attitude. Technically average, endurance average, but because of his attitude he ran more than he usually did, but he was a leader."

Wagner left for top-flight side Schalke, where he won the 1997 Uefa Cup, while at the same time Klopp and Mainz were finishing fourth in the German second division, although he would never play in the Bundesliga.

Hearts & Mainz: Klopp & Wagner

"Every friendship develops with time and then it develops a trust and belief in each other," Wagner said. "We had such a strong base in the first four years, so even when I was at Schalke and he was in Mainz, we always stayed in contact."

One of the biggest influences on Klopp's career was Wolfgang Frank, a coach who played a high-tempo style of football and a back four at a time that Germany was obsessed with sweepers.

But after he left Mainz for a second time in 2000, the club went through three coaches in under a year. Bravely, they then turned to their 34-year-old defender.

"It was a big surprise I came a manager to everybody," Klopp recalls. "I did my badges and finished my studies during my playing career. I was the youth coach at Eintracht Frankfurt very early when I was 20, 21.

"And I had the fantastic situation where the club thought I could do it immediately."

While Klopp was enjoying life as Mainz manager, his best mate was quitting football altogether.

"I was 30, 31, I played the last two seasons before in Bundesliga 3 and I was no longer hungry and greedy to play as a professional," Wagner said. "I thought I have to be more outside of this football family."

Klopp was having his own agonies as Mainz coach, twice getting the exciting team to the brink of a first-ever top-flight promotion, but twice they were denied on the final day of the season.

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In 2004, however, Maniz were at last promoted and the relationship between the pair was now so close that when Klopp got married, he asked his big buddy to be best man.

Wagner brought Klopp and the stag party to Mainz city centre.

"In Germany, we have a Christmas market and in Mainz, they have one of the biggest Christmas markets in Germany," Wagner remembers.

"We put Santa Claus masks on us and there were 25 Santa Clauses, because Jurgen was not able to go in the Christmas market as a normal person. But everybody recognised that here was a group to join Klopp to celebrate!"

Klopp was celebrating again after keeping Mainz in the top division for two more seasons, despite the odds. But after relegation and just missing out on promotion, it was time for change.

Klopp was off to awaken one of the Bundesliga giants and at Borussia Dortmund, he would link up again with Wagner.

Dortmund were one of the great names of German football, but when Klopp arrived there in 2006, they were not in good health, sitting 13th in the Bundesliga.

Playing at full gas, though, Klopp produced a young, vibrant side that was thrilling to watch.

"The first season, we were supposed to go to Europe, but only missed it by an inch," said Neven Subotic, who played under Klopp at both Mainz and then Dortmund.

"The next year, we went to Europe and the year after that we won the championship. So it was just a rocket ride to the top."

I like heavy metal. I love it when I read after the game that we ran more that the opponent

Klopp had put Dortmund back on top in Germany.

"I like heavy metal more," he said. "I love it when I read after the game that we ran more that the opponent. I like this. If somebody tell me after the game that you ran 11km more than the other team, that is good. I do not like winning with 80 per cent."

This young, charismatic coach was becoming one of the most famous men in Germany and the man who was never good enough to play in the Bundesliga was now king of the Bundesliga.

It would get even better as Klopp was to be joined at the club's training ground on a daily basis by his best man after Wagner decided he too wanted a crack at football management.

"When he came to Dortmund, it was not my idea", Klopp said. "I would have loved to work together with him, but I never brought a friend in before."

There was no stopping Dortmund, who won the Bundesliga in 2011 and 2012. The next season, they produced some memorable Champions League displays, including an incredible semi-final win over Real Madrid.

However, they would lose the final to Bayern Munich at Wembley. Key players then left, ironically to the Bavarians, whose massive financial superiority over Dortmund began to take its toll as they claimed three Bundesligas in a row.

Klopp announced he was leaving the Westfalenstadion, with the German eventually joining Liverpool in October 2015.

It was thought Wagner would follow Klopp to Anfield, but the next month he moved to Huddersfield.

"There are no truth in these rumours," insists Wagner. "This was totally independent from Jurgen's decision to go to England and go to Liverpool."

Wembley was again to prove an unhappy hunting ground for Klopp as Liverpool lost the League Cup final on penalties to Man City in February 2016, while Wagner was just happy to finish 19th in the Championship.

Last season, though, would prove the most significant in Wagner's football career as he guided the Terriers to the play-off final at the home of football.

"I was in the South of France at a friends' house and we watched it on television," said Klopp of May's clash between Huddersfield and Reading.

"He asked me if I wanted to come, but I feel a little bit sorry for him as I really think he is big and strong enough, and what he has achieved so far is big enough, so nobody has to mention he is best man of Klopp.'

"I did not want to come in the stadium and have one camera on me and see how I react when he should be, or his team, in the middle of all interest.

"So I did not want to play this part and we watched it and I was nervous like hell. And afterwards, Ulla [Sandrock, Klopp's wife] sent him a video of me crying like a baby when it happened, the final penalty, as I could not stop."

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And now, more than a quarter of a century after they met for the first time at Mainz, the duo are rival managers in the English Premier League.

"Nobody expected it, even when I joined Huddersfield," Wagner said. "We met already in friendlies when he joined us here at the John Smith's Stadium once and we played one friendly behind closed doors in Melwood.

"But this now, Anfield, he in one dugout, I in one dugout, this will be strange for sure."

What happens, though, if there is a last-minute winner on Saturday afternoon?

"If we score the winner, I will celebrate for sure," said Wagner. "And I know he will celebrate as well if he scores the winner!"

His best mate agrees, saying: "And on this day, we will do everything to beat Huddersfield, for sure. And after that, we will have a talk like it is always."

Watch 'Hearts and Mainz: Klopp & Wagner' at 6.30pm and 8.30pm on Sky Sports Premier League on Friday, as well as On Demand.