Iker Casillas was a bored schoolboy, clock-watching, trying not to fall asleep when Real Madrid knocked on his classroom door to pull him out of his technical drawing lesson and fly him off to Norway in 1997.
There was an injury crisis among the club's keepers and they needed the 16-year-old apprentice to play a Champions League group game against Rosenborg.
His decision, to quit just ahead of his 38th birthday, means he falls short of fulfilling his ambition to play on until he is 40.
But it's about the only dream he couldn't quite reach – everything else came to him in an extraordinary 22-year career.
'They pulled me out of school because Bodo Illgner and Santi Canizares were injured and they needed me as a second keeper,' he said of that day back in November 1997, in an interview with Sportsmail.
Canizares ended up recovering and the young Iker was only Real's third keeper but coach Jupp Heynckes still told him to get changed and take his place on the bench.
'I knew who they all were, but no-one had a clue who I was,' he said of his illustrious team-mates.
He would end up becoming one of the club's most famous sons winning the European Cup three times. First he was the youngest keeper to achieve the feat in 2000 against Valencia.
Two years later he wasn't picked to start against Bayer Leverkusen at Hampden but when Cesar Sanchez picked up a foot injury Iker – 'Saint Iker' as adoring supporters would come to call him – came on for the last 20 minutes and made three brilliant saves to ensure Madrid won the final.
That was Madrid's ninth European Cup and a full 12 years later Casillas would still be in goal when they won their 10th.
As a young keeper he never stood out for what he could do with his feet and he was not one for dominating his area but he could do one thing better than any of his peers – stop the ball hitting the back of the net – and that made him the world's greatest for so long.
For pure shot-stopping there was no-one better. And that fundamental forte never mattered more than when Arjen Robben was bursting through in the 2010 World Cup final and Casillas came out to deny him with an outstretched right leg.
That as much as Andres Iniesta's goal would win Spain the World Cup.
When he won his third Champions League in Lisbon it represented a remarkable comeback. It takes a certain type of toughness to survive at Real Madrid and when Jose Mourinho took over as manager he soon made it clear he wanted a new keeper.
When a phone call from Casillas to Barcelona's Xavi, after yet another Clasico had descended into an ugly brawl, ended in reconciliation, Mourinho did not like the olive branch that had been held out by one of his players.
The saga played out alongside the soap opera of the 'Madrid mole' with Casillas chief suspect in what appeared to be a leaky dressing room giving away Mourinho's team selections before they were officially announced.
Mourinho urged the club to buy another goalkeeper and eventually dropped Casillas for 26-year-old reserve team keeper Antonio Adan.
The feud divided supporters with some siding with Mourinho against Casillas but when Carlo Ancelotti replaced Mourinho he made Casillas keeper for European matches enabling him to win his third Champions League in Lisbon.
He moved to Porto in 2015 and won the 2017-18 league there. He lapped up the life away from the goldfish bowl existence that Madrid can become.
Time has washed away any sense of divided opinion back in the Spanish capital. After his recent heart scare nowhere was his name chanted louder by supporters than at the Bernabeu.
Messages of support flooded in with former Real Madrid team-mate Cristiano Ronaldo, posting on social media: 'A lot of strength my friend. I hope you recover soon.'
All his friends in football wanted him to put his health first even if that meant quitting. Although he ruled nothing out when he emerged from hospital to face reporters last week he has decided to finally draw a line under his remarkable career.
Remembering that first sample of Champions League football as a 16-year-old he told Sportsmail: 'I was taken to the headmaster and before I knew it I was on a school minibus going home, where my mum was frantically packing my bag for me.'
It was only the beginning of an incredible journey. He has plenty to look back on now, and a more impressive trophy haul than perhaps any other keeper in history.
