Less than 200 metres separate Barcelona's 98,600-capacity Camp Nou from the 16,000-seater Mini Estadi. There is even a walkway linking the two stadiums, like an umbilical cord between the baby and the mother ship. Yet the gap between being a regular performer at the Camp Nou and the Mini Estadi is vast.
As well as staging the home games for Barca's B team in Spain's second tier, the smaller stadium is the site of the Catalans' games in the inaugural NextGen league - a 16-team, Champions League-style competition for Under 19 teams from western Europe's leading clubs, such as Barcelona, Ajax, Marseille, PSV Eindhoven, Liverpool, Sporting Lisbon and Inter Milan.
Other grandees, such as Manchester United, Real Madrid and Bayern Munich, are expected to join.
The competition is aimed at mimicking the Champions League and giving the best young players experience of travel and playing against different styles of football in western Europe.
Earlier this month, at the Mini Estadi, Barcelona's most promising youngsters took on their equivalents from Manchester City. Barca won 4-1.
The league, which launched in August and will culminate with the finals in January, is the brainchild of two British men. Mark Warburton, a former professional footballer and City trader, who became the academy manager at Watford, and Justin Andrews, whose background is in television.
"We'd both worked closely with Europe's top clubs and we approached those clubs first about the league," Andrews said. "We wanted to set up a league which helped bridge the gap between youth football and the first team."
They also sought to provide a learning environment for players to experience how best to cope with the pressures of top-level football. "We played some pilot games, they were a success and we got the league started," Andrews said.
Though the league is intended to mimic the experiences of the first team, Barcelona will not let their young players speak to the media.
But Barca take every other element of the league seriously.
A lack of consistency in how football is played below first-team level in Europe ensured the NextGen league has plenty of voids to exploit.
In England, reserve-team football is widely seen as an inadequate stepping stone towards the first team; Manchester City did not enter the reserve league this season.
"We didn't enter because the domestic reserve league is inconsistent," said Andy Welsh, the coach who joined City from Manchester United after helping oversee the development of players such as Darron Gibson, Fraizer Campbell and Ryan Shawcross, all of whom play in the Premier League.
"Sometimes we were coming up against teams of very young players, other times senior players. That didn't help the development or progress of our best players."
Welsh is a fan of the Spanish system, where reserve teams are allowed to climb the football pyramid up to the second tier. Their players also benefit from performing in front of crowds, being on television, dealing with the media and playing against experienced pros who are desperate for a win bonus.
Both Manchester giants thus feel that their best 18 and 19-year-old players are better served going out on loan, but the NextGen tournament is a step in the right direction and City have embraced it, even if their results have not been all they would have hoped.
"It has been a very positive experience for all involved," says Welsh. "The levels of the teams we've played against are far superior to the levels of the teams we've played before. That only tests our players to the best of their ability."
Standards have been so high, Welsh said, "that it gives the players some idea of the levels they have to reach if they want to make our first team, where the standard is unbelievable".
He added: "We're playing against world-class players for their age group and that's who we want our players to be playing against."
Replicating the philosophy of their first team, City are investing heavily in their youth set-up. In September, they unveiled plans for a youth development and first-team academy, which will include space for 400 young players, 11 youth pitches, four first-team pitches and a stadium with a capacity of 7,000.
Among their young players are Denis Suarez, a Spanish U17 midfielder whom City bought from Celta Vigo in north-west Spain in June for £850,000 (Dh4.95m), which could rise to £2.75 million depending on appearances.
Another is Karim Rekik, a central defender, who looks older than his 16 years. He was a star in the youth ranks at Feyenoord, the Dutch club, before joining City in the close season. Like Suarez, he has impressed enough to taste first-team football this season. The young Blues also boast the Norwegian U21 goalkeeper Eirik Johansen, Andrew Cole's son Devante and Juan Angel Roman, a cherubic Catalan back on home turf after he was signed from Barca's neighbours Espanyol. Like their neighbours United, City now cast their scouting net far and wide, but having lost all five matches so far against Barca, Celtic and Marseille - they play their final game, against Marseille, on Thursday - the City team are a work in progress.
Barcelona have the advantage of a settled system, and their team features the latest in their production line of talent through the Masia academy. Samper, the midfielder, is hailed as the new Xavi, while the left-back Grimaldo is highly rated.
The striker, Sandro Ramirez, had a crowd of 600 - City and Celtic have attracted crowds greater than 2,000 - applauding three times as he hit a hat-trick on the way to Barcelona's victory against City.
Patrick Vieira, the former France and Arsenal midfielder, and now City ambassador, was in the stands watching.
"The players are learning from playing different styles of football," he said. "They're also learning to be footballers with all the travel, dealing with the media and playing in stadiums. I would have liked that when I was their age."
The players agreed.
"I've played against Barcelona many times because I'm from here, but it's fantastic for my teammates to come and play here," Roman said. "The league helps us develop as players because we play against completely different styles of players. Marseille were very physical, while Barcelona have a lot more possession, just like their first team. It's good for us because we have to adapt, but it's good for us as people, too. We're living like footballers now, travelling, staying in hotels and speaking to the media, like now."
City are the only one of the 16 teams not to pick up a point in the four-team group competition so far, but Roman is not perturbed.
"At our level, it's more about player development than the result. It's disappointing that we've lost every game and that we won't be going to the finals, but we'll just have to try our best next year."
It is not about results for Barcelona, either, according to their coach, Oscar Garcia, who played with the first team as a midfielder in the 1990s.
"Some teams probably still have the idea that it's about winning and they take decisions differently on who to play," he said. "For us, it's about formation and learning, it's not about winning."
The organisers have made the league happen and they will need to look at sponsorship and television rights in the future to fund the league.
While domestic reserve-team football will suffer even more, it's good, so far, for the next generation.