There are no prizes for guessing which of the two clubs involved in Tuesday night’s big game at Stamford Bridge played a bigger part in producing the players wearing their colours.
In terms of those who played, Andreas Christensen was the height of it from a Chelsea perspective with the Danish centre-back having signed from Brondby on a free two weeks short of his 16th birthday. Okay, not everyone playing for the visitors can claim to have had blue and garnet, as Barca themselves describe their colours, flowing through their veins from birth but 15 and 11 months sets the bar pretty low.
Of the Barcelona starters in London, Sergi Roberto, Andrea Iniesta, and Lionel Messi are amongst those to have either come from the Catalonia, joined the club very early or both. A couple of Ernesto Valverde's players have taken diversions on their path from the club's academy - La Masia - to the first team with, most obviously, Gerard Pique having had a spell at Manchester United while Jordi Alba was released at 16 for being too small and later sold by a local club to Valencia for €6,000 (Everton eat your heart out). Even the €14 million Barca paid to get him back looks like a bit of a steal at this stage, though.
For the hosts, only unused sub Callum Hudson-Odoi really shared the sort of status we are talking about here on this occasion with the young forward having been born in Wandsworth and signed for the Premier League outfit when seven. He is just 17 now and had his first nine minutes of the senior team football in the cup a few weeks back.
He is widely lumbered with the tag of “wonderkid” but time will tell whether he gets to pursue his career at Chelsea or, as with so many before him, they opt to cash in and put the money towards the price of a product of somebody else’s youth development system.
Some sense of where the young players who have successfully navigated the best of those across Europe was provided this season by the Swiss sports research group, the CIES Football Observatory who published a list of the 50 young (none yet 21) players they consider to be best placed at present to establish themselves at a high level based on the games they have played to date in the continent’s better leagues.
It makes for interesting reading with, for all the money being spent by England’s cash rich sides, some alarming trends enduring. The Bundesliga, for instance, is far better represented than the Premier League, something that reinforces the notion that German clubs are far more open to giving young players a chance to progress.
In England, the likes of Ryan Sessegnon at Fulham, Liverpool Trent Alexander-Arnold and Everton's Tom Davies are all playing for clubs based in their area. Alexander-Arnold grew up around the corner from Liverpool's Melwood training ground and he is said to have been spotted playing by an academy coach - but recruitment in a couple of other instances appears to have been based on the sort of early international movement of players that often doesn't end so well for the families involved.
Manchester City have two players on the list but neither is counted amongst England's five representatives as both - Brazil's Douglas Luiz and Manu Garcia from Spain - are amongst the 18 players that the club currently has out on loan. Ajax, by contrast, have three, winger Justin Kluivert, centre-back Matthijs de Ligt and midfielder Carel Eiting, all from the greater Amsterdam area and all currently based at the club.
Others have already crossed continents to pursue their dream. Toulouse goalkeeper Alban Lafont, Bayer Leverkusen's Panagiotis Retsos and Leeds United midfielder Ronaldo Vieira are amongst the eight African born prospects and 12 from outside Europe. A very significantly disproportionate number of the rest are the sons of immigrants (although even more disproportionately, at least 10 per cent are the sons of professional players) with French still seeming to lead the way.
Houssem Aouar at Lyon, Sofiane Alakouch of Nimes and Toulouse's Kelvin Amian Adou, for instance, were born in the catchment areas of the clubs for which they play to families whose origins are in Algeria, Morocco and the Ivory Coast respectively.
The league here badly needs to succeed in providing Irish teenagers with a viable alternative
Kylian Mbappé, whose parent are from Cameroon and Algeria, might be considered the stand-out star of the bunch and his international future is already resolved with the 19 year-old into double figures for caps with France but others, like Stuttgart midfielder Berkay Ozcan have already shifted from representing the country of their birth at international level to the one in which their family’s roots lie.
Despite their youth, the vast majority have changed clubs at least once and while most have simply moved up the chain in the way that would be expected, quite a few have already made multi-million euro moves. Mbappé's, when it is complete, will dwarf the rest but Martin Odegaard moved to Real Madrid for something like €4 million, an amount that might yet double even if it seems less likely to now. Wolfsburg paid Dinamo Zagreb €6 million for striker Josip Brekalo and Leverkusen handed over almost three times that for Retsos who had already firmly established the scale of his ability at Olympiacos after having arrived in Greece from South Africa.
Ismailia Sarr, as it happens, turned down the opportunity to join Barcelona, preferring to take his chances with Ligue 1 side Stade Rennais, persuaded perhaps by the long list of players who have used the club as a stepping stone to bigger things and the fact that the fee of €18 million or so that Metz wanted for him undoubtedly meant a lot more to the French club than it would have to the Spanish giants.
Over at Nice, Malang Sarr, no relation is seems although his parents are from Senegal and Ismailia was born there, has also been attracting the attention of the La Liga leaders too it seems. Spend any time reading through the cuttings for the 50, though, and it is astonishing, or maybe ridiculous, the number who, despite mainly still being in their teams, have apparently interested the Premier League outfits.
Most would do well, it seems, to steer clear until their careers cannot be derailed by one unwise move but some of the moves already made suggests that the money on offer is often too good to turn down. The ability of sides like Chelsea, who write a cheque of the size required to make up for its own failure to produce players of the standard required, is just one more reason the league here badly needs to succeed in providing Irish teenagers with a viable alternative to progressing their career here at home.