Andre Villas-Boas has been confirmed as Chelsea's new manager.
The former Porto boss has signed a three-year deal and is in London on Wednesday preparing to begin work.
Villas-Boas, 33, is the same age as players Frank Lampard and Didier Drogba and won the Portuguese league, League Cup and Europa League last season.
"Andre was the outstanding candidate for the job. He is one of the most talented young managers in football today," Chelsea said in a statement.
"He has already achieved much in a relatively short space of time. His ambition, drive and determination matches that of Chelsea and we are confident Andre's leadership of the team will result in greater successes in major domestic and European competitions.
"Andre will bring his coaching experience back to a club he is already very familiar with, having previously worked here for three years. He has always been highly regarded at Chelsea and everyone here looks forward to welcoming him back and working with him."
Chelsea paid the £13.3m compensation to release the Portuguese coach from his Porto contract, with Villas-Boas succeeding Carlo Ancelotti, who was sacked after a trophyless season.
Former Chelsea boss John Hollins believes Villas-Boas could prove to be a shrewd acquisition for the west London club, who are yet to realise owner Roman Abramovich's dream of winning the Champions League, and were beaten in the quarter-finals by Manchester United last season.
"He could be fearless," Hollins told BBC Sport. "I think it could be a breath of fresh air, bringing in a fresh approach to this maybe tired football team.
"This guy is as young as some of the players are so he will be on the same wavelength with them, but is it going to be a three or four-year programme as opposed to having to win something in his first year? That is the one thing we don't know yet, but he has won three competitions in Portugal just like that, so he could be a whizz-kid.
"It's a gamble but I think it's a calculated gamble. I still don't know if Guus Hiddink will be coming as an adviser to the young man. If he does, that will only strengthen the position."
Former Chelsea winger Pat Nevin agrees with Hollins that the appointment of Villas-Boas is a "calculated gamble".
"There is always a risk with every managerial appointment but he is highly regarded as one of the up and coming young European coaches and has been successful in domestic and European competition," Nevin told BBC Sport. "He is flavour of the moment and Chelsea have seen something in him."
Under Villas-Boas last season, Porto were unbeaten in the league, with 27 wins in 30 matches, becoming only the second Portuguese club to complete a league campaign without losing a game, after Benfica in 1972-73.
A scout for compatriot Jose Mourinho at Porto, Chelsea and Inter Milan, Villas-Boas began his managerial career with Portuguese club Academica in October 2009.
Academica were winless and bottom of the first division at the time but finished the season in 11th place.
They also reached a Portuguese League Cup semi-final before he left to take over at Porto in June 2010.
Villas-Boas, who speaks fluent English, also worked with Sir Bobby Robson during the former England manager's spell in charge of Porto.