Some of the most exciting footballers in the world have not even hit the age of 21 yet.
Here are 11 of the world's best players under the age of 21, with their market values courtesy of Transfermarkt.
Goalkeeper: Thibaut Courtois | Atletico Madrid (on loan from Chelsea)
The young Belgian international was loaned out by Chelsea to Atletico Madrid for a period of two seasons. Purchased from Genk by the Blues in the summer of 2011, Courtois has since managed to earn himself a starting line-up position with Atletico, as well as 10 caps with the Belgian national team.
Currently valued at £13m at 20 years of age, Courtois is considered to be the replacement for Petr Cech, whose performances have slightly diminished over the past couple of seasons.
Right-back: Mattia De Sciglio | AC Milan
At the end of his second season as a professional, De Sciglio has proven himself to be a fierce defender. For AC Milan manager Massimiliano Allegri, the youngster is the perfect competition for Ignazio Abate. In fact, due to the latter's injuries this season, it was young Mattia who has been used more regularly this season.
This position was a difficult choice with FC Porto player Danilo also showing a lot of promise, as well as the young Spaniard Daniel Carvajal.
The Italian is valued at £7.9m at just 20 years of age.
Centre-back: Raphael Varane | Real Madrid
The young French prodigy was bought from RC Lens by Real Madrid in 2011. It was around this winter that young Varane imposed himself as number one in the centre-back hierarchy, outranking Pepe and even Sergio Ramos in the eyes of the manager Jose Mourinho.
He has recently earned his first two caps with the French national team against Georgia and Spain. Raphael has displayed a great deal of maturity and talent since joining Madrid and is believed to be the next best defender on the planet. At 19 years of age, he has a market value of £17.5m.
Centre-back: Matija Nastasic | Manchester City
The names of numerous other young starlets come to mind for this position, such as Kyriakos Papadopoulos or Phil Jones. However, it is the Serb who has been used more regularly than the others and has proven himself to be a valuable purchase for Manchester City since the beginning of the season.
In his first season with the Citizens, Nastasic is already used almost as often as Joleon Lescott and Kolo Toure combined. Matija, at 20 years old, has a value of £15m.
Left-back: David Alaba | Bayern Munich
This is probably the easiest position to choose for. David Alaba is a definite starter with Bayern Munich and for obvious reasons. The Austrian possesses an incredible passing ability as well as technique, speed and the ability to keep calm in any given situation.
The 20-year-old already counts no less than 24 international caps with Austria and three goals. Alaba has a market value of £19.5m.
Midfield: Paul Pogba | Juventus
Since joining Juventus, Pogba has had quite a season. Although not yet a guaranteed starter with the Bianconeri, the youngster has done well to excite the Italian and French supporters.
His performances, as well as his physical build, have earned him several comparisons to a certain Patrick Vieira. Having just turned 20 years old, Pogba is valued at £11m.
Midfield: Mario Gotze | Borussia Dortmund
Although it was a tough choice between him and Chelsea starlet Oscar, it was the German who deserved it more in my eyes.
Gotze has, this season, shown more consistency and is more valuable to his team. With incredible focus, composure and pure talent, young Mario might take a leap in his career to a different destination this summer, be it Arsenal, Manchester City or anywhere else, he should not have too much trouble settling in. At 20 years of age, he is already valued at £37m.
Midfield: Jack Wilshere | Arsenal
Where to begin? Jack Wilshere has already established that he is one of the best footballers on the planet. This season, especially, he has become the star and saviour of Arsenal.
Debate had begun a while ago over whether or not there were still any true English style midfielders left in the world. With Steven Gerrard and Frank Lampard getting older, not many worthy replacements came to mind, until Jack Wilshere came along. At 21 years of age, he is valued at £24.5m.
Right-wing: Lucas Moura | PSG
Having recently joined Paris St. Germain from Sao Paolo, it did not take long for the Parisian fans to fall in love with their new starlet.
Very impressive with the ball at his feet, this youngster displays an incredible dribbling ability, speed and spontaneity that is rarely found these days. I believe he could be a future Ballon d'Or winner. He is 20 years old and has a value of £31m.
Left-wing: Stephan El Shaarawy | AC Milan
Touching on the end of his second season with AC Milan, El Shaarawy's talent was previously hidden by other forwards such as Zlatan Ibrahimovic, Robinho or Alexandre Pato.
This season, however, the young Italian has completely eliminated any competition be it in his club or in the Italian national team. The 20-year-old is valued at £20m.
Striker: Neymar | Santos
There really is no debate when it comes to deciding who is the greatest young centre forward in the world.
Neymar has been the subject of many compliments over the past three years. It seems that no one can end the discussion over where the Brazilian will go after the 2014 World Cup, or if he will ever even leave his beloved Santos. At 21 years old, Neymar is currently worth £44m.
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