Chelsea have today secured the long-term services of academy graduate Billy Clifford.
The English full back, who can also play in the midfield positions, is highly-rated at Stamford Bridge and was involved in first-team activities last term.
Clifford signed his first professional forms with Chelsea last summer, and featured in pre-season against Ajax last year.
He was also in a Chelsea Champions League squad, but failed to make a competitive appearance for the Blues under Carlo Ancelotti.
The 19-year-old has clearly impressed Andre Villas-Boas during the Porto manager's short time at the club, having feature in pre-season this term too against Portsmouth.
He will now remain at Chelsea until 2015.