Tiago's on board

Chelsea have finally completed the signing of Portuguese midfielder Tiago in a deal that could rise to £8million.

The Benfica midfielder finally put pen to paper on a three-year contract at 11pm last night after a day of frantic negotiations at Stamford Bridge and will fly to America with his new team-mates today.

Tiago's move to Chelsea appeared a formality after the player passed a medical on Monday but threatened to break down in a series of talks yesterday.

Benfica wanted a clause inserted into Tiago's contract preventing him from being sold on to another Portuguese club but Chelsea refused. There was also disagreement over the fee structure before Chelsea finally agreed to pay £6m up front and a further £2m depending on bonuses and appearances.

Tiago is Jose Mourinho's fourth signing for Chelsea and takes their summer spending spree to £49m, while the club have spent an astonishing £190m on new players since Roman Abramovich's takeover a year ago.

A fifth could follow with Chelsea chief executive Peter Kenyon indicating that a central defender is a priority. Mourinho is short of cover to back up John Terry and William Gallas.

Chelsea were considering a £3m move for AC Milan's 22-year-old Argentinian defender Fabricio Coloccini but are now likely to look elsewhere. Mourinho could now shift his focus to Deportivo La Coruna's Jorge Andrade.

Tiago, 23, has been Mourinho's first choice to fill the final midfield position in his squad since the collapse of Steven Gerrard's proposed £36m move last month and he should be relatively fresh after a quiet summer. He was part of the Portugal squad that reached the final of the European Championship but failed to add to his 10 caps.