The players aged 21 or under who are considered to be the most valuable.
Sport is always looking towards youth and in football this can also involve some very huge transfer sums for players who are barely legal to drink in a bar.
Here are the 20 most valuable youngsters aged 21 or below according to transfermarkt.com.
18=. Iker Muniain
Club: Athletic Bilbao.
This young winger has been in the first team squad for an incredible four years and has already played 187 matches in all competitions for Athletic.