Deco arrived at Chelsea from Barcelona, for a fee of around £7million, on Monday night and instantly declared that he can help the Blues become the best team in the Premier League and in Europe.
The talented playmaker, who became new coach Luiz Felipe Scolari's first signing, had recently been told by the Catalan club he did not feature in their future plans and had been consistently linked with a move to the west London club in recent months.
The 30-year-old has signed an initial two-year deal but it is understood that could be extended.
Deco, who won the Champions League and UEFA Cup with Porto, said: 'It is good for me to be here and first of all I am very happy to be here.
'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.
'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
'To have great players in any position just enhances the club. 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 but I am sure I will adapt quite well and quite fast and do my best for the team.'
Deco is Chelsea's second signing of the summer after international team-mate Jose Bosingwa.
But his arrival will only add to speculation over Lampard's future.
Chelsea now have Michael Ballack, Michael Essien, Mikel Jon Obi, Claude Makelele, and Lampard in their midfield and with the club intent on reducing their squad, it is clear a number of players will leave.
Scolari must persuade Lampard, currently on holiday off the coast of Italy, to sign an extended deal or face the prospect of losing him to Jose Mourinho's Inter Milan.
Lampard has one year remaining on his current contract and the midfielder seemingly refused to rule out a move to Milan when quizzed over his future.
Ricardo Carvalho's future is equally as uncertain, although Deco's signing may help the new Chelsea coach to persuade the defender to stay.
Chelsea were planning to hold contract talks with the Portugal international, who has only just started a holiday because of his involvement in Euro 2008.
However, Brazil defender Alcides claims he is returning from a loan spell at PSV Eindhoven to replace him at Stamford Bridge.
Alcides has been on loan at the Dutch club for the last 18 months, and said: 'PSV wanted me to stay but I have learned that Chelsea want me back. It seems Carvalho is leaving and I am going to replace him.'