Chelsea yesterday completed the €5 million (Dh26m) signing of Oriol Romeu from Barcelona on a four-year deal.
The 19 year old is the second arrival of the Andre Villas-Boas era, and will link up with his new teammates at the end of Spain's Under 20 World Cup campaign in Colombia.
Barca confirmed Chelsea had paid €5m for the midfielder, with the deal including a buy-back clause of €10m after one year and €15m after two.
The fee was agreed 11 days ago for the midfielder, who was quoted this week as saying: "Chelsea is a great option for me.
"Leaving Barca hurts, but you have to take your chances."
Oriol's agent, Magico Diaz, reportedly jetted out to Columbia this week to seal the deal.
Oriol played 90 minutes in Spain's opening two 4-1 and 2-0 victories over Costa Rica and Ecuador respectively at the Under 20 World Cup.
His arrival at Stamford Bridge will help offset the loss of Michael Essien, who faces six months out with a serious knee injury.
Villas-Boas said: "It is a part of the squad in which we are struggling with numbers, because of Michael Essien's injury, and Oriol is a player with a bright future. He still has to evolve as a player.
"The Barcelona B team had a magnificent year in the Spanish second division, they finished third. Oriol had an injury during the season but he came back late on and was in time to play for the first team. So he is one of the most promising young players in that position."
Oriol, who is 6ft and can also play in central defence, made his first team debut for Barca at the end of last season but Pep Guardiola, the coach, deemed him surplus to requirements.
Chelsea have already signed the Belgian goalkeeper, Thibaut Courtois from Genk, immediately loaning him out to Atletico Madrid.
They have seen two bids for Luka Modric rejected this summer and were this week pondering to make a third and final offer for the Tottenham Hotspur playmaker.
There have also been reports linking Yuri Zhirkov and Alex with moves away from Stamford Bridge.