Many football fans first became aware of Jose Mourinho in a Uefa Champions League last-16 tie against Manchester United in March 2004.
The current Chelsea manager was in charge of Porto back then, with his touchline antics at Old Trafford catching the eye.
A 1-1 draw on the night saw Porto triumph 3-2 on aggregate, with Mourinho ultimately leading the Portuguese club to the trophy in what was one of the competition’s greatest success stories, in terms of the underdog triumphing, in recent history.
Fast forward 10 years and another young manager was making a similar impact on the side of the pitch in a key European encounter.
In April 2014, Diego Simeone’s Atletico Madrid dismantled Mourinho’s Chelsea 3-1 at Stamford Bridge, booking their place in the Champions League final after a performance of typical vigour and gusto.
Over on the touchline, Simeone was animated and energetic, coaxing and cajoling his players in the manner that his opponent in the home dugout that night had become famous for.
It was like winding back the clock.
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If Mourinho does depart Stamford Bridge — Roman Abramovich has demonstrated uncharacteristic patience and restraint so far, but a parting of the ways looks increasingly likely — Simeone is the man Chelsea should target as their next manager.
The Argentine has done a truly sensational job at Atletico since his appointment in 2011.
His first campaign in charge ended with the Europa League trophy, in 2011/12, before the Copa del Rey was captured with a famous victory over Real Madrid at the Bernabeu the following campaign.
The 2013/14 season saw Atletico win the Primera Liga against all odds. Given their financial disadvantage in relation to the big two in Spain, it was arguably one of the greatest accomplishments in the history of the Spanish game.
They also reached the Champions League final after that aforementioned win over Mourinho’s men in the last four, and were just seconds away from beating rivals Real to the crown before a last-minute Sergio Ramos equaliser sentthe gameinto extra time, where Real ran away with the trophy.
Chelsea-bound Diego Costa, Thibaut Courtois and Filipe Luis were among the players who left that summer, but Atletico consolidated with a third-place finish in the Liga.
After heavy investment in the summer, another challenge for the championship looks possible this term.
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Simeone’s charges find themselves second in the table after 16 matches, level on points with leaders Barcelona and five ahead of Real Madrid.
Atletico are a supremely well-organised unit who are difficult to break down; their record of nine clean sheets and seven goals conceded is testament to their defensive solidity.
They play with aggression and intensity, and are happy to cede possession and hit opponents on the counter-attack. In other words, Simeone’s favoured style of play is extremely comparable to Mourinho’s.
The latter has grown tired this season, worn down by an extraordinary collapse that nobody could have predicted when Chelsea lifted their fourth Premier League title in May.
While his track record and trophy haul speaks for itself, the doubts about Mourinho’s suitability to longer-term jobs have re-emerged.
The 52-year-old Portuguese has never completed a fourth season at any of his six clubs. If the intention was to remain at Chelsea for many years to come, circumstances have made that eventuality hard to envisage.
With frequent managerial changes an inevitability in the modern game, it is important for sides to have some sort of continuity in terms of structure and identity behind the scenes.
Guus Hiddink, Carlo Ancelotti, Roberto di Matteo and even Rafael Benitez all did good work at Stamford Bridge, but Chelsea is a club that has been built in Mourinho’s image since he first arrived in West London and announced himself as the “Special One” in 2004.
The Argentine Simeone shares many similarities with Mourinho, both in personality and playing philosophy.
If Mourinho does move on, Simeone would be a natural replacement.
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