From a gangly, unknown teenager to one of the best goalkeepers in world football.

It’s fair to say Thibaut Courtois made quite an impact in his three years on loan at the Vicente Calderón, and returns to parent club Chelsea a hero after helping us to the La Liga title.

As we all know, the chances of signing Courtois on a permanent deal were always slim, and the confirmation of Jan Oblak’s signature from Benfica has all but ended any chance of a fourth season in red and white for the big Belgian. But despite never actually being our player, Tibu will never be forgotten.

Some may not be aware, but Atlético were actually in competition to sign Courtois from Genk along with Chelsea back in 2011 and were close to securing a deal, but as soon as the Blues got involved we were unable to compete on a financial level.

Having just won the league title for his hometown side, the 19 year-old was loaned to us as replacement for David de Gea. However, when pictures emerged of the young stopper arriving at Barajas airport, many fans were dismayed.

“Why can’t the club spend money and look for an established goalkeeper? Is this guy any better than Joel Robles? Why are we loaning and developing players for other clubs?” were some of the questions posed. How wrong they were.

Courtois made his debut in a 4-0 win over Vitória Guimarães back in August 2011 to secure our place in the Europa League group stages, a competition he played a big part in us going on to win. Since then, he never looked back.

With David de Gea enduring a tough couple of months in England after leaving us for Manchester United, Tibu was shining in a struggling Atleti side then managed by Gregorio Manzano. It did not take long for fans to label him as being better than his popular predecessor though, and without him things could have gotten a lot uglier.

A moment that stands out from his early days at the club, for me, was a save against Sevilla a couple of months into the campaign. It was a drab, 0-0 encounter that we were expected to win, but were ultimately saved embarrassment thanks to a stunning Courtois save from Jesús Navas. Although just 19, he read the situation perfectly and showed strength and bravery impossible for one so young to stop the Spanish international from winning the match.

Simeone’s arrival in the new year led to the Europa League triumph, and Courtois would further endear himself to the Rojiblanco faithful in the European Super Cup against, of all teams, Champions League winners Chelsea. In a memorable 4-1 win, Tibu made no effort to hide where his allegiances lay and went on to take a leading role in the ensuing celebrations – not for the last time.

The 2012-13 campaign would perhaps be his most significant on the banks of the River Manzanares. Atleti returned to the Champions League and Courtois was presented with the Zamora trophy, given to the goalkeeper with the best games to goals conceded ratio in La Liga. We also saw the birth of Thibauting, an Internet sensation created by our own Martin Rosenow that went all around the world.

Courtois would then go on to break a long-standing club record set by Abel Resino in the 1990’s, as he went 820 minutes without conceding in the Vicente Calderón – a spell that lasted over four months. However, the crowning glory came at the end of the season, with a performance that will live in our history as we not only won the Copa del Rey, but also beat rivals Real Madrid for the first time in 14 years.

It was a monumental effort from all the team, but Tibu’s superhuman stop to thwart what looked to be a certain Mesut Özil goal in injury time will always be remembered. The young stopper had already made incredible stops from Gonzalo Higuaín amongst others, but that save, when it looked for all the world as if los Blancos had equalised, was one of the best I’ve ever seen.

As Cholo and his team embarked on Neptuno the next day to celebrate such a historic win, Courtois put an end to the wishes of Real Madrid fans who were hoping their club would steal him from under our noses.

“Salta, salta, salta, pequeño canguro, que a los Madridistas les den por el culo…” he sang to thousands from the balconies overlooking Puerta del Sol. We’ll leave the translating down to you.

Now, with a league title and a second Golden Gloves award under his belt, Tibu leaves the Spanish capital as one of the finest goalkeepers ever to don the red and white jersey. Perhaps even the finest.

Countless times on our way to winning La Liga, his interventions were key. He had a brilliant defence in front of him, but without an even more brilliant young Belgian between the sticks, what we achieved would never have been possible.

As the season wore on and the team began to tire, often we had to rely on individual inspiration to provide that little bit extra. Tensely having to defending slim one-goal leads in the closing stages of matches became a common theme, but thanks to he and the defence, on most occasions we were able to pull through.

Saves at San Mames in the win at Athletic – labelled a turning point by Simeone – in the Coliseum against Getafe, at home to Espanyol despite having almost been knocked out with 15 minutes on the clock, and in countless other battles were the making of our heroic conquest, and I think fans will really appreciate just what an incredible goalkeeper we were privileged to have now that he has gone.

At just 22, there is no doubt Courtois could go on to become one of the all-time greats in his position, and hopefully he will remember his time at Atleti as the foundation of his career. Last week he visited our training complex in Majadahonda to clear his belongings and say his goodbyes, although we will surely see him return at some point, perhaps defending the visiting team’s goal this time.

Hasta siempre, Tibu.