Two years later, Leverkusen even managed to miss three chances to win silverware within a few days, manifesting the image of a club that would always come up short.

Fast forward to this season and any lingering doubts about Leverkusen's ability to handle the pressure were swiftly dispelled weeks before Sunday's title success.

Under the leadership of Xabi Alonso, their dominance has been relentless, marching towards their maiden domestic championship with an air of inevitability.

They've been a juggernaut, unbeaten thus far, eyeing not just the Bundesliga crown but also tantalising prospects of a treble, with the German Cup and Europa League also still within reach.

While Leverkusen were considered part of Bundesliga's potential top three going into this season, few gave Alonso's team a fighting chance against Bayern Munich, especially with the perennial champions' marquee summer signing of England captain Harry Kane.

Leverkusen's resurgence traces back to Alonso's arrival, injecting a fresh impetus into a team that was 17th in the Bundesliga standings at the time the 42-year-old took over.

The transformation from an underperforming group of undoubtedly gifted players into a cohesive unit who are unbeaten this season is testament to Alonso's tactical acumen and leadership skills.

When he first stepped foot into Leverkusen's facilities, the former Liverpool, Real Madrid and Bayern Munich midfielder was still an inexperienced coach, having only managed Real Sociedad's reserves during the three previous years.

Alonso has acknowledged on many occasions he is continuously learning and far from the finished product. But despite his relative inexperience, he had the foresight to let Leverkusen play their transition-orientated style during the remainder of the previous season, before he deliberately changed the tactical approach entirely.

As a result, Leverkusen have become one of the best-working possession sides in Europe that can control the pace of games and frustrate opponents with long spells of ball retention.

Such a change in style is unusual and also came unexpectedly, not least because Alonso, the manager, was still an unknown commodity going into this campaign.

Of course, German football fans knew about his achievements as a player and watched him especially closely during his final three years on the pitch as a player when Alonso conducted Bayern's midfield from 2014 until 2017.

However, other former top-class players from Alonso's generation have proved in recent years that a great playing career does not automatically lead to success in the managerial world.

That said, very few have appeared as thoughtful as Alonso. It is very fitting that, despite all the rumours and interest from Bayern Munich and Liverpool, he decided to stay with Leverkusen for at least another year. Alonso does not seem in a rush but rather wants to mature further.

Ex-Arsenal man embodies Alonso

Granit Xhaka has made 41 appearances in all competitions for Leverkusen this season

As much as Alonso deserves the praise, he obviously could not have won the German championship without a group of players willing to buy into his ideas of football and able to execute them in close-to-perfect fashion.

From key defender Jonathan Tah to explosive winger Jeremie Frimpong to the highly-talented attacking midfielder Florian Wirtz, it is hard to single out individuals. Arguably, the one player who has impressed most this season is Granit Xhaka.

To many, the 31-year-old's switch from Arsenal to Leverkusen last summer might have seemed a step down for an ageing midfielder. However, the Swiss international has reinvigorated his career by going to a place where he can be a leader instead of a mere bit-part player.

In a sense, Xhaka embodies the Alonso type of midfielder, as the attack usually goes through him as he determines the rhythm and direction of each play.

In the past, Xhaka has often hit the headlines due to his outspoken personality and politically-charged statements. But he's been nothing but a true leader and helping hand for Alonso since his arrival.

Xhaka was one of five major summer signings who have enjoyed a genuine impact, with the others being goalscorer Victor Boniface, wing-back Alex Grimaldo, and wingers Jonas Hofmann and Nathan Tella.

Leverkusen paid combined transfer fees of £59m for the quintet - considerably less than Bayern paid Tottenham for Kane alone.

Leverkusen beat Harry Kane's Bayern Munich 3-0 at home in February

The England captain, 30, moved to the record German champions to finally win some silverware.

Unfortunately for Kane, he joined Bayern at the worst possible time. Despite all the well-paid talent on the club's books, manager Thomas Tuchel has not been able to form a well-functioning unit and create a lasting bond with part of the dressing room, which ultimately led to the decision to part ways at the end of the season.

With Kane set to continue under a new manager, Bayern will aim to reclaim their dominance in German football.

While Leverkusen's brilliance this season has been undeniable, thwarting the Munich outfit's resurgence next year will pose a formidable challenge.

Nonetheless, Leverkusen, guided by Alonso, have etched their names into the annals of history with a remarkable achievement.