Things have rarely been more exciting when it comes to young footballers. Superstars are emerging earlier and earlier, some of them before they even leave school. We've seen 15-year-olds handed Premier League minutes and teenagers challenging for the Ballon d'Or, even as their peers in their 30s continue to thrive and show us we might need to rethink upper and lower limits of what's possible in the game. And there are plenty of other up-and-comers ready to step into the shoes of the current crop of young starlets.

We have taken a look at some of those superstars-in-the-making, as well as those who can already call themselves superstars at a young age. Express Sport's list here comprises 21 players aged 21 or under, all of whom have made their mark at European clubs. This isn't a definitive list - we're sure you can point to some who you think deserve a spot on the list. For now, though, we've kept our focus on the bigger hitters in Europe, with particular attention to those coming through the ranks in the Premier League and other big five leagues. Without any further ado, here they are...