It's amazing to think that Kylian Mbappé is still 21, which means that he qualifies for a slot in this combined XI.
We've consulted the data provided by the talented people at squawka, who have put together their best U21 combined XI across Europe's top five leagues for 2019/20. Here are those players and some of our additional thoughts.
🇮🇹 Gianluigi Donnarumma
The AC Milan goalkeeper has kept more clean sheets (8) than any other Serie A goalkeeper this season.
🏴 Trent Alexander-Arnold
The English right-back is the first player in Liverpool's history to provide 10+ assists in multiple Premier League seasons.
🇫🇷 Dayot Upamecano
RB Leipzig's commanding French centre back has won 14 aerial duels in the Champions League this season. He was particularly impressive against Tottenham.
🇳🇱 Matthijs de Ligt
Juventus' young Dutchman is the first defender in history to win the prestigious Golden Boy award, in 2018.
🇲🇦 Achraf Hakimi
The versatile Moroccan has completed more take-ons than any other defender in Europe's top five leagues in 2019/20. If he leaves Borussia Dortmund at the end of his two-year loan at Signal Iduna Park, the 21-year-old will be missed. He's set to return to parent club Real Madrid.
🇫🇷 Eduardo Camavinga
The 17-year-old Rennes midfield wonderkid has won more duels (184), tackles (93) and fouls (51) than any other U21 player in Europe's top five leagues this season.
🇳🇴 Martin Ødegaard
The talented Norwegian playmaker has created more chances than any other U21 player in Europe's top five leagues this season, becoming the creative force in a Real Sociedad side sitting in 4th on the LaLiga table. He might well be strutting his stuff back at Real Madrid next season if Los Blancos elects to keep him after what has been an impressive loan spell away.
🇩🇪 Kai Havertz
Elegant German creative midfielder Kai Havertz has directly contributed to 68 goals (38 goals & 30 assists) in 139 matches for Bayer Leverkusen across all competitions. He's still only 20.
🏴 Jadon Sancho
20-year-old Jadon Sancho was the first player in Europe to reach double figures for both goals & assists this season, doing so when he was still 19. Sancho has directly contributed to 55 goals (26 goals & 29 assists) since the start of 2018/19; only three players have contributed more.
🇳🇴 Erling Håland
Norwegian teenager Håland already has 12 goals & two assists in 11 Borussia Dortmund appearances.
🇫🇷 Kylian Mbappé
PSG superstar Mbappé has directly contributed to 63 goals (51 goals & 12 assists) since the start of 2018/19. Only Lionel Messi (80) has contributed to more in that timeframe. How is this man still only 21?
What a stunning array of talent, and that's not even considering the likes of Sandro Tonali, Reece James, Gabriel Martinelli, Bukayo Saka, Billy Gilmour, Mason Greenwood, Vinícius Júnior, Alphonso Davies and more!