London:Deco transferred to Chelsea from FC Barcelona on Monday, reuniting with former Portuguese national team manager Luiz Felipe Scolari at Stamford Bridge.
The signing is the first for Chelsea since Scolari announced during the European Championship that he was leaving the Portuguese side for the London club, and comes a day before he officially takes charge.
"It is good for me to be here and first of all I am very happy to be here," the 30-year-old Deco said. "I know it is a new challenge but I am looking forward to it.
"I know I need a little bit of time to adapt bit but I am sure I will adapt quite well and quite fast and do my best for the team."
Scolari was able to lure Deco despite interest from Jose Mourinho at Inter Milan, but Chelsea could lose midfielder Frank Lampard, who has been linked with a reunification with Mourinho at the San Siro.
Deco was shown on Chelsea's Web site signing the contract with chief executive Peter Kenyon, although details of it weren't initially disclosed.
Deco had two years left on his contract with Barcelona, but new coach Pep Guardiola said last week that the Brazil-born midfielder wasn't part of his plans for next season.
He was barely known in Brazil and was even released by local club Corinthians before venturing into small Portuguese clubs Alverca and Salgueiro.
It was there he attracted the attention of top clubs, eventually moving to FC Porto and Barcelona.
He won the European Champions League with both Porto and Barcelona, and becomes part of the latest attempt by the Blues to claim first European Cup title.
"I am sure I have come at the right time to do great things and be able to help Chelsea go back to the way it was, and come back to being the first one, not only in England but also to win the Champions League that has been their dream for so long," he said. "The Premier League is a great league and it is getting better and you can see that with the Champions League Final, where you had two English teams.
"It is great that we have so many great players here at Chelsea and it is great that there is the competition which is healthy for everybody and this just makes the team better."
Plagued by injuries, Deco scored only one goal in 28 matches with Barcelona last season. He was among several players jeered by fans in the team's last home appearance in the Spanish league. He said it was his "worst season" with the club and was allowed to negotiate with other teams.
He was part of the Portuguese squad that reached the Euro 2004 final on home soil, losing to Greece. He also helped Portugal reach the 2006 World Cup semifinals, when it lost to France. But at Euro 2008, the pre-tournament favorite lost to Germany 3-2 in the quarterfinals.