When Inter Milan drew Barcelona in the semi-finals of the 2009-10 Champions League, few backed the Italian side to progress against Pep Guardiola’s world-beaters.
Both were chasing their own piece of history. Barcelona were trying to become the first team to claim back-to-back titles in the Champions League era while Inter were seeking a first European Cup final since 1972 and a first win in the competition since 1965.
It was a tie tinged with bitterness, with Inter boss Jose Mourinho going up against Guardiola, who had worked together at Barca but were now intense rivals.
It was a tie that defined Mourinho as a coach and ultimately saw him lead Inter to the Treble – the first Italian side to achieve such a feat – as they wrapped up the Serie A title, the Coppa Italia and the Champions League.
And on 28 April 2010, he and Inter took a mighty leap towards that historic achievement.
Fifteen years on from the captivating second leg in Barcelona and with the two preparing to face each other in another Champions League semi-final, BBC Sport takes a look at the story of that fascinating tie.
The Special One v the king of tiki-taka
Tension had been brewing long before the players set foot on the pitch.
In the summer of 2008, Barcelona were looking for a new manager, having sacked 2006 Champions League winner Frank Rijkaard.
The choice was Mourinho or Guardiola, who had worked closely with the Portuguese during the 1990s when he was Sir Bobby Robson’s assistant and the Spain midfielder was Barca’s captain.
It was a position Mourinho had acquired having first started out as an interpreter for Robson at Sporting, before evolving into an assistant coach. He followed Robson to Porto then Barca.
But while in Catalonia, the Portuguese was disgruntled with his treatment.
He was nicknamed ‘the translator’ and felt he was not taken seriously.
When it came to Barca appointing a new coach a decade later, Mourinho – who by then boasted Champions League and Premier League titles on his CV – was shunned in favour of Guardiola, who had just finished his first year in management with Barca’s reserves.
It was a decision that did not sit well with Mourinho and had a profound impact on the way he would go on to set up his teams, sacrificing pretty football – like Guardiola’s tiki-taka – in favour of efficiency a solid defence.
Barca’s decision instigated a managerial rivalry between Mourinho and Guardiola that came to a head in 2010 in the tie and was later ramped up while the former was at Real Madrid.