10 youngsters to watch in 2019: Vinicius Junior headlines exciting group

Over the next 12 months, a new wave of youngsters will begin to make their mark on football. Here, theScore takes a look at the most promising players aged 21 and under across the top five European leagues.

Matthijs de Ligt

• Ages: 18
• Club: Ajax
• Positions: Defender

De Ligt's likely to command a massive transfer fee in 2019, with the likes of Manchester City, Barcelona, and Paris Saint-Germain circling above. Excellent with his feet and calm in possession, the center-back became the first-ever defender to win the Golden Boy award as the best Under-21 player in Europe this year. Ajax teammate Frenkie de Jong just missed making this list, but the skilled 21-year-old midfielder is bound to secure his own big-money move in the summer.

Christian Kouame

• Age: 21
• Club: Genoa
• Position: Winger

Genoa striker Krzysztof Piatek is all the rage, but teammate Kouame deserves plaudits as well. The 21-year-old's set up the Pole on multiple occasions and won the second-most aerial duels in Serie A this season. He's the yin to Piatek's yang, as someone who does the dirty work and tracks back while his strike partner busies defenders. Kouame is more than just a pacy prospect; he's smart with the ball and tricky to defend. AC Milan reportedly made an approach for Kouame in recent months, and more suitors are likely to follow.

Carles Alena

• Age: 20
• Club: Barcelona
• Position: Midfielder

Barcelona officially promoted Alena to the first team at the beginning of December as cover for the injured Rafinha - a welcome development for supporters who'd begged the club to graduate more youngsters from La Masia. And in just four appearances, the 20-year-old's discipline and work rate have already impressed manager Ernesto Valverde. Alena and fellow academy alum Riqui Puig should provide hope that Barcelona's identity will remain intact.

Aaron Wan-Bissaka

• Age: 21
• Club: Crystal Palace
• Position: Right-back

If Wan-Bissaka was a secret before Crystal Palace's win over Manchester City on Dec. 22, he certainly isn't now. After winning Palace's player of the month award for August, September, and October, he confirmed his rise with a man of the match performance against City. He's also second in the Premier League in completed tackles and third in interceptions, showing both the pace and the discipline on the right flank to nullify his opposite number. Having played as a winger in his formative years, the 21-year-old possesses the attacking instincts that managers want in a modern-day full-back.

Brahim Diaz

• Age: 19
• Club: Manchester City
• Position: Attacking midfielder

City manager Pep Guardiola said his club will do "absolutely everything" to keep Diaz - whose contract expires in the summer - but there's no guarantee. Jadon Sancho made City look like fools for letting him go last year and the same could happen if Diaz chooses to leave. The 19-year-old can't find a way into City's lineup even with his incredible technique and dribbling ability. Real Madrid are reportedly prepared to offer him an escape, but it's hard to believe the midfielder would get significantly more playing time with the reigning European champions. Next year will be crucial to his development.

Ismaila Sarr

• Age: 20
• Club: Rennes
• Position: Winger

Sarr's been turning heads due to his performances on the wing this season. Capable of playing on both the left and right, the 20-year-old has the confidence to take on defenders and shoot from distance. He's already scored a number of spectacular goals - many from the edge of the penalty area - but often takes a few too many risks with the ball. A proper manager could give Sarr the discipline needed to become a world-class player.

Reiss Nelson

• Age: 19
• Club: Hoffenheim (on loan from Arsenal)
• Position: Winger

Arsenal can rest easy knowing Reiss Nelson will return a better player, as he's enjoyed his first few months on loan at Hoffenheim, scoring six goals across 13 Bundesliga appearances. And while he's a winger by trade who can run past defenders, Nelson's much more than a traditional speed merchant - he's also difficult to dispossess and makes himself available in the middle of the pitch. If the 19-year-old continues to progress under Julian Nagelsmann, he should find himself in Arsenal's lineup by the start of next season.

Lucas Paqueta

• Age: 21
• Club: AC Milan
• Position: Midfielder

Paqueta's the next big thing from Brazil. Milan somehow beat out Madrid and Paris Saint-Germain to sign the 21-year-old, who's slated to make his Serie A debut sometime in the new year. A creative midfielder who can play in various areas of the pitch, Paqueta's been lauded for his versatility and defensive commitment. He's certain to get playing time at Milan - who are crying out for midfielders following long-term injuries to Lucas Biglia and Giacomo Bonaventura - and is in line for more appearances with the Brazilian national team.

Vinicius Junior

• Age: 18
• Club: Real Madrid
• Position: Winger

Real Madrid promoted Vinicius to the first team this season, and with the help of manager Santiago Solari, the Brazilian could make an even greater leap next year. Solari coached the 18-year-old on Madrid's youth team and brought the youngster up to the senior squad with him. A €45-million signing from Flamengo, Vinicius has earned three starts to date, impressing Madridistas with his direct approach to goal and flashy skills. The club may already have its heir to Cristiano Ronaldo.

Moussa Diaby

• Age: 19
• Club: Paris Saint-Germain
• Position: Winger

Thomas Tuchel's somehow found a way to give academy graduate Diaby playing time in Paris Saint-Germain's otherwise crowded attack. A left winger who likes to take on defenders, the 19-year-old has scored twice and recorded five assists in just 11 Ligue 1 appearances this season. Diaby's also allowed Neymar to take up more central areas of the pitch while showing a willingness to track back. Tuchel told a handful of young players they'd get minutes this season, and so far he's kept that promise.