Jurgen Klopp has warned the rest of Europe that Borussia Dortmund will only continue to get better.
BVB won many fans with their exhilarating run to last season's Champions League final, where they were defeated by a late winner from Bundesliga rivals Bayern Munich, but, despite routing Real Madrid 4-1 in the first leg of the semi-final this year, the coach is confident that there is more to come.
Klopp told Uefa's official websiTE: "We haven't reached our peak in terms of performance yet but, if we look at our results last season, then we almost achieved it.
"We still don't have a clue how well the team can play, we still have to show that."
The 46-year-old has instigated an incredible turnaround since taking over at the Signal Iduna Park in the summer of 2008, winning two Bundesliga titles and the 2012 DFB-Pokal, while he was twice named Germany's coach of the year. Klopp, however, insists that that "I'm no magician".
"We cannot make good players out of bad players," he explained. "We need to recognise the potential in the right players, try to develop it to turn it into skills with the help of everyone involved. That's how you can find success.
"Generally I think we can make a team better with the way we work, with the way we train."
Dortmund have been grouped alongside Arsenal, Marseille and Napoli in Group F of the Champions League but Klopp is reluctant to predict a similar European adventure to last year, admitting that his side struck lucky en route to Wembley.
"You can only reach the final by also being lucky in some situations. No team makes it to the final just because they're the best and strongest team," he continued.
"We were certainly not the best team and therefore we needed a bit more luck. You also need a big heart, great desire and then we can make it a long way but we might also be knocked out in the group stage.
"In the Champions League the quality of the other teams is just too high. It would have been crazy if we had won the Champions League last season.
"Only a few lads thought they would become Bundesliga players and five years later they became domestic champions twice and won the German Cup once - and to have then become Champions League winners, that would have been an incredible story.
"You need a playing philosophy that reflects your mentality, that reflects the club, that gives a direction to follow," Klopp continued.
"That means taking the passion to its limits. Borussia Dortmund don't just play for a result, Borussia Dortmund means an experience."