The U21 Youth Cup is a tournament similar to the national cup, but for U21 teams. Any team with a U21 team at the start of the season is included in the Youth Cup.
The Youth Cup is first held in season 10 in any country that has at least 8 U21 teams at the start of the season.
The rules are the same as for the national cup. A single match is played and the winner advances to the next round. Teams from higher leagues enter the cup in later rounds and have to play away against teams from lower leagues. The last team remaining is the winner.
Not all teams start in the same round. The seeding order is based on the level of the teams in the upcoming season. Within the same level the teams are ordered by popularity. For example, the last 4 teams to enter the cup are 4 teams from level 1 in the regular league with the highest popularity.
If there are less than 8 teams in your country with a U21 squad you will not have a national U21 Cup. Instead you can participate in the U21 Cup for small countries. Seeding in this tournament is done by popularity, the higher your popularity the later you'll enter the tournament.
The home advantage is decided in the same way as in the normal cup. The higher level team has to play away. If both teams are from the same league level the home team is decided randomly. Like the U21 league there are no visitors to these matches so there is no stadium income, but there is home advantage.
Every player gets 270 experience points for his first 3 matches in the Youth Cup. Unlike the U21 league, the match counter is not shared with the normal cup, so a player can get experience in 3 Youth Cup matches AND 3 normal Cup matches.