A selection of some previous transfers involving teenagers.

ANTONIO CASSANO

Italian striker Cassano became the world's most expensive teenager when he secured a £20 million move to Serie A giants Roma from Bari in June 2001. Financial problems have forced Roma to sell a number of players but Cassano and club talisman Francesco Totti are too precious to be sold.

RONALDO

Barcelona paid £16 million to sign Ronaldo from PSV Eindhoven as a 19-year-old in 1996. After one season and 38 goals, he moved to Italy's Inter Milan.

JAVIER SAVIOLA

Barcelona paid £15 million to Argentinian giants River Plate to sign Javier Saviola in 2001 when he was a 19-year-old. Joined Monaco on loan yesterday.

CRISTIANO RONALDO

Towards the end of last season the winger began to demonstrate why Alex Ferguson was willing to pay Sporting Lisbon £12.24 million for his services.

ROBBIE KEANE

Coventry signed Robbie Keane from Wolves for £6 million when he was just 19 in 1999 but only held onto him for a season before Inter Milan bought him for £13 million after he had turned 20.

JERMAINE JENAS

Bobby Robson invested £5 million to take 18-year-old Jermaine Jenas from Nottingham Forest. After settling quickly into life at St James' Park Jenas was handed an England call-up.

DIEGO

Porto quickly replaced inspirational playmaker Deco by signing highly-rated Santos star Diego for around £4.8 million after their star player moved to Barcelona. The 19-year-old was inspirational in Brazil's Copa America success and won praise around the world for his mature performances.

RICARDO QUARESMA

Barcelona paid £4 million for Quaresma in 2003. The 19-year-old's dream move from Sporting Lisbon went sour as his relationship with Barca boss Frank Rijkaard deteriorated rapidly, prompting a move to Porto.