Since then, the transfer record for a teenager has multiplied almost eight-fold.
Let’s take a look at the five most expensive transfers involving players under the age of 21 (all values via Transfermarkt):
5. Christian Pulisic (Borussia Dortmund to Chelsea, £57.60m)
The highly-rated American winger Christian Pulisic initially signed for Chelsea in January 2019, although it wasn’t until the beginning of the next season that he would make his debut for the club.
As a result of the move, he became the most expensive American footballer of all-time.
4. Matthijs de Ligt (Ajax to Juventus, £76.95m)
Matthijs de Ligt became the most expensive defender under the age of 21 when he joined Juventus from Ajax in the summer of 2019.
The transfer followed one of Ajax’s most successful Champions League campaigns. They came within a few seconds of reaching the final of Europe’s biggest continental competition before Lucas Moura’s famous late goal sent Spurs through instead.
Two of the team’s most vital members – de Ligt and Frenkie de Jong – would leave the club that summer, with de Ligt joining the Italian giants.
He has since established himself as one of his new side’s key defenders, and won Serie A in his first season.
3. Joao Felix (SL Benfica to Atletico Madrid, £114.48m)
After a breakthrough season at Benfica, where he scored 15 goals in 26 Primeira Liga appearances, Joao Felix moved to Atletico Madrid for a fee of £114.48m in 2019.
It hasn’t all been plain sailing in Spain so far for the 21-year-old, although he has contributed effectively to Atletico’s LaLiga title-winning campaign this term.
2. Ousmane Dembele (Borussia Dortmund to Barcelona, £121.50m)
Barca made their move for the Frenchman just weeks after Neymar departed for PSG in the summer of 2017.
Despite showing his immense quality when fit and available, Dembele’s time at Barca has been headlined by a number of injuries.
He missed four months of his debut season due to injury. The forward then played just five times in the 2019/20 season, mainly due to a hamstring tear in February that ruled him out for the rest of the campaign.
He did make 30 appearances for Barca in the most recent campaign, scoring on six occasions and combining well with Lionel Messi.
1. Kylian Mbappe (AS Monaco to Paris Saint-Germain, £130.50m)
The Frenchman initially joined the Parisians on loan in 2017, scoring 13 goals in 27 league appearances.
That move was then made permanent, with Mbappe going on to reach new heights. He won the World Cup with France in 2018, becoming the second teenager behind Pele to score in a World Cup final in the process.
He has won Ligue 1 on three occasions, was named the 2017 Golden Boy and was included in the 2018 and 2019 FIFPro World11.
Featured Image Credit: Getty