The first few seasons of Jurgen Klopp's managerial career – way back at the turn of the millennium – were a lot like his first few seasons at Liverpool: One effervescent, enthusiastic, exciting and positive ride, reaching so close to the ultimate goal. Overachieving, but just short of the pinnacle.

In Klopp's first season at Mainz, he saved the club from relegation from the 2. Bundesliga to the third tier of German soccer. The next two seasons, he produced well above expectations, putting the club on the precipice of promotion to the Bundesliga for the first time in the club's history, but finished one place behind promotion both times.

The next season, in true Klopp form, Mainz took their promotion charge to the final day of the campaign again, but they needed a win plus another result to go their way. He reached out to a player he began recruiting for a little help: Current Colorado Rapids interim manager Conor Casey, then a striker for Karlsruher SC.

“That week I get a text [from Klopp], ‘come on now, help us out,’" Casey told MLSsoccer.com last week. "We ended up winning 1-0, I scored. There’s a clip of him on the field afterwards going like ‘who scored?’ They told him Casey, and he goes, in German, ‘I adopt him!’ A week later, I signed the contract and I was in Mainz.”

Thanks to Casey's goal, Mainz earned promotion to the Bundesliga. It's a feat Klopp says will always be his biggest achievement.

During three ultimately disappointing years for the American international under Klopp, Casey didn't know it, but he was learning the foundation of his own coaching style – from a man who would go on to win two Bundesliga titles and reach three UEFA Champions League finals, the latest of which unfolds on Saturday with Liverpool against Tottenham in Madrid.

Conor Casey (far left) and Jurgen Klopp (far right) at Mainz in 2004 | Mainz 05

Casey is at the beginning of his own coaching career, joining the Rapids' coaching staff as an assistant in 2017 before being named interim head coach at the beginning of May. He inherited a side at the bottom of MLS, winless over the first two months of the year, but worked to reverse the culture immediately. He has since led the club to back-to-back wins, a feat almost unfathomable prior to his appointment.

Both by way of man management and tactics, Casey espouses a lot of what Klopp embodied. And it's paying off.

“One side of it is the managerial part and the positivity part, which I believe in very much," Casey said. "Supporting your players and trying to be a positive force for the team. The other part is the transitional nature of how we trained, which I’m doing now with the club. Distances, spaces, reactions – a lot of different drills to train that.”

While Casey doesn't describe it as Klopp's now-infamous "heavy-metal football" moniker, the new Rapids boss carries a strong influence from Klopp. The transitional nature of how he wants his Rapids side to play – for however long he's in charge – harkens back to what he learned in Germany.

“I’m already trying to turn that direction with our team," Casey said. "It takes time and personnel to go that direction; I’m trying to implement those ideas. The way soccer is going now – it’s a transitional nature. Regardless of what style you play, transition is so important right now. It just depends where you want to do it on the field. It’s something I completely believe in. I played for him, I played for [current RB Leipzig head coach] Ralf Rangnick. I have a very good grasp on the way to train it, the mentality and physical nature, of it.”

Casey caught Klopp's eye with a breakout campaign that season, scoring 14 goals in 30 matches while on loan with Karlsruher SC. He was the third-leading scorer in the division for 2003-04.

During it, Klopp began a recruiting process that he has been consistent with throughout the years, from Casey to Robert Lewandowski to Mo Salah to Virgil van Dijk and many, many more between. It requires a long meeting between Klopp and the perspective signee: He wants to know the person behind the player.

“We talked more about life, not so much about soccer," Casey said. "He wanted to get a general sense of me as a person. He’s a very friendly person, he’s very good at getting peoples’ guards down and getting a sense of the person.”

On the field, it didn't work out to Casey's plan. After three years, with fives goals over 42 appearances, it was time for a change. After a brief stop at Toronto FC, Casey landed with the Rapids, where he spent six fantastically successful seasons.

“It was amazing," Casey said of his time under Klopp. "His enthusiasm, personality, rapport with the players, essence and positivity is something I still remember and took with me from my time there.”

Jurgen Klopp at Mainz in 2003 | Action Images

Casey has overachieved the nonexistent expectations he inherited when he took charge of the Rapids, another trait he seems to have taken from Klopp.

“I’ve had a lot of influences, but Klopp is a big one for sure," Casey said. "I’m not that type of personality, but I certainly believe in the positive messaging and reinforcement. I believe that’s the right way to coach. And tactically, yes. It was a long time ago, but he’s evolved a lot in his tactics. But I’ve been around a lot of very good coaches in my career, so I feel fortunate.”

On Saturday, before Casey and the Rapids host FC Cincinnati (8:30 pm ET | MLS LIVE on ESPN+ in US, DAZN in Canada), he'll be watching his old mentor take on Tottenham in the Champions League final, hoping to finally get over that final hurdle.