"We don't have mandatory release of the players, which means there are a number of players who won't be released by their clubs," England coach Brian Eastick said before the 2011 tournament. "So we accept that. Even if we did have mandatory release, we would still have to be sympathetic to some players who are playing first-team football at the top level."
Fifa acknowledge the issue: "We cannot force anyone to come - that is not possible," said Marion Mayer-Vorfelder, Fifa's head of the Under-20 World Cup. "[But] we have put the [tournament] in the June window now - the best for release, because that is when the European leagues break. We are very hopeful for that period."
Recent editions have been held in October or July, which precluded some top players (clubs wouldn't allow them to miss a month of action) and the switch to June is promising.
It's also an issue that varies across federations. Some, like Argentina, have clauses inserted into their players' contracts that make release mandatory (perhaps why La Albiceleste have won the tournament a record six times) while the English FA depend on club goodwill. Even if a few players are unavailable, it will still be a great opportunity to see a huge amount of talent, some of whom will go on to be among the best in the world.
"It's quite incredible when all of a sudden you see a player like Messi and you think, 'wow, who is that?"' says Mayer-Vofelder. "Then a few years later, he is World Player of the Year and you are the one that has seen him first time."
Meanwhile, in a nod towards New Zealand's friendly reputation, some of the stadia at next year's event will be permitted to have standing areas. Fifa usually insist on all-seating stadiums but made an exception at the 1999 Under-17 World Cup in New Zealand (at North Harbour Stadium) and will do so again next year at Stadium Taranaki and Waikato Stadium.
Tickets for the 52 match tournament, which is staged across seven venues, will go on sale from next month. The opening game is May 30 with the final on June 20.