The UEFA Youth League's relevance is emphasised by the list of talented young players who have graduated from the junior competition to star at the very top of the game.
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In its six-year history, the UEFA Youth League has already proved an important testing ground for exciting young talents across Europe – as this lineup of Youth League graduates who have sparkled in the current UEFA Champions League season illustrates.
GK: Mile Svilar (Anderlecht, now Benfica)
Made 15 appearances over three seasons, helping Anderlecht reach back-to-back UEFA Youth League semi-finals in 2015 and 2016 before joining Benfica and becoming the youngest goalkeeper in UEFA Champions League history when debuting in October 2017 against Manchester United aged 18 years and 52 days.
RB: Trent Alexander-Arnold (Liverpool)
A UEFA Champions League finalist against Real Madrid last May, Liverpool's adventurous right-back had gained his first taste of competitive international action against the same opponents in the UEFA Youth League in November 2014 – making the first of two outings in the 2014/15 competition in the Spanish capital 28 days after his 16th birthday.
CB: Presnel Kimpembe (Paris)
Featured seven times in the competition in 2013/14 and has since graduated to the big stage with Paris and the France national team, scoring his first UEFA Champions League goal at Manchester United in February.
CB: Matthijs de Ligt (Ajax)
A pivotal figure in Ajax's run to this season's UEFA Champions League semi-finals, the outstanding young centre-back made the last of his ten appearances in the UEFA Youth League in February 2017 – and three months later was playing in the UEFA Europa League final against Manchester United.
LB: Lucas Hernández (Atlético)
Made five appearances, scoring twice, in the autumn and winter of 2015/16 – and ended that campaign appearing for Atleti's seniors in a UEFA Champions League quarter-final against Barcelona.
RW: Jadon Sancho (Man. City/Dortmund)
Scored on his competition debut for Manchester City against Borussia Mönchengladbach in September 2016 and also shone in the UEFA Youth League for Dortmund with three goals in five outings in 2017/18, before subsequent dazzling displays for both Dortmund's and England's senior sides.
DM: Lorenzo Pellegrini (Roma)
A UEFA Champions League semi-finalist with Roma last season, having helped Roma get to the same stage of the UEFA Youth League in 2014/15, making nine appearances.
AM: Leroy Sané (Schalke, now Man. City)
The City flyer played 13 times in the competition for first club Schalke, helping them into the last four in 2013/14. A month after his final appearance in the UEFA Youth League in February 2015, he hit his first UEFA Champions League goal for Schalke against Real Madrid aged 19.
LW: Kingsley Coman (Paris, now Bayern)
Turned out seven times for Paris in 2013/14 and within 12 months was making his UEFA Champions League debut for Juventus. By summer 2016, aged 20, the Bayern winger was playing in the UEFA EURO 2016 final for France.
FW: Marcus Rashford (Man. United)
Nothing illustrates Rashford's rapid rise better than the fact that five months after his two goals on his UEFA Youth League bow against PSV in September 2015, he was scoring twice on his senior United debut against Midtjylland in the UEFA Europa League.
FW: Kylian Mbappé (Monaco, now Paris)
The French FIFA World Cup winner made a single outing in the UEFA Youth League – for Monaco on 9 December 2014 – 11 days before his 16th birthday. By the following December, he was in Monaco's first team.