Belgium's goalkeeper Thibaut Courtois dives for the ball before a quarter-final match against Argentina at the Mane Garrincha National Stadium in Brasilia on July 5, 2014 during the 2014 FIFA World CupBelgium's goalkeeper Thibaut Courtois dives for the ball before a quarter-final match against Argentina at the Mane Garrincha National Stadium in Brasilia on July 5, 2014 during the 2014 FIFA World Cup (AFP Photo/Evaristo Sa)
London (AFP) - As the Premier League's leading clubs step up their preparations for the 2014-15 season, some of their most promising young talents are stepping out into the unknown.
With teams like Chelsea and champions Manchester City boasting huge, star-studded squads, their younger players have no option but to go out on loan in search of the playing time vital to their development.
For some players it can prove a richly rewarding experience.
Belgium's Thibaut Courtois has returned to Chelsea after a three-year period at Atletico Madrid that saw him emerge as one of the world's finest goalkeepers.
Courtois's club and international colleague Romelu Lukaku has also benefited from time on loan, excelling at West Bromwich Albion and Everton, although it seems he has yet to convince manager Jose Mourinho of his worth.
Joel Campbell harbours hopes of breaking into the first team at Arsenal, meanwhile, after an impressive season with Olympiakos that provided a launchpad for an excellent World Cup with Costa Rica.
For others, however, the loan system can feel like being trapped in a revolving door.
Gael Kakuta, a precociously skilful attacking midfielder, joined Chelsea from French club Lens at the age of 16 in 2007, sparking a row that momentarily saw the English side banned from signing players.
After he made an eye-catching debut against Wolverhampton Wanderers in November 2009, then coach Carlo Ancelotti was moved to declare: "At that age I have never seen a player with this talent."
However, with established players such as Joe Cole and Florent Malouda cemented in Chelsea's starting XI, Kakuta found his route to the first team blocked.
There followed a succession of underwhelming loan moves -- to Fulham, Bolton Wanderers, French club Dijon, Dutch side Vitesse Arnhem, and Lazio -- and at 23, his career is still awaiting take-off.
- Perpetual loanee -
"I don't dream about Chelsea anymore. I used to, but now I know better," Kakuta complained last year.
"Chelsea have far too many players. At my age, I need to play regularly, but if I go back I'll just get 10 minutes a month, and I don't want that."
Chelsea loaned out 27 players last season -- with six going to Dutch side Vitesse, with whom the London club have a strategic partnership -- but technical director Michael Emenalo says the policy is well-intentioned.
"The loan process at Chelsea has become very professional and a good deal of thought has gone into it," he told the club's website.
"We don't send players out because we are trying to recover some money. We send them because we want them to play and develop and we want to monitor them."
Eight Chelsea youngsters have already agreed loan moves for the coming season.
They include the Nigeria international Kenneth Omeruo, who has returned to Middlesbrough, and Thorgan Hazard, younger brother of first-team star Eden, who has joined Borussia Moenchengladbach.
At Arsenal, 21-year-old forward Wellington Silva -- who played alongside Neymar for Brazil's under-17s -- is gearing up for a fifth consecutive loan spell, this time at Spanish side Almeria.
It is a path similar to the one trodden by Mexican forward Carlos Vela, who was successively loaned out to four clubs by Arsenal before finally leaving for Real Sociedad in 2012.
Andros Townsend knows more than most about being a perpetual loanee, having played for nine different clubs before finally getting a chance to shine at Tottenham Hotspur, but he says the experience was worthwhile.
"At a massive club like Tottenham opportunities will come, but not straight away," he told The Daily Telegraph earlier this year.
"You have to get out there and prove that you deserve to have them coming your way. The only way that's going to happen is if people see you playing. It makes you."