Chelsea, which beat Portsmouth, 4-0, on opening day, leads the EPL on goal difference over Liverpool, the only other team to open with two wins.
The win took Chelsea, who were far from their best, to the top of the standings with six points, the same as Liverpool who have also won their opening two games although Chelsea has a better goal difference. The Reds rallied for a 2-1 win over Middlesbrough on Saturday on own goal from Emanuel Pogatetz in the 86th minute and a strike deep into stoppage time from Steven Gerrard gave them victory.
With midfield partners Michael Essien, Frank Lampard and Michael Ballack playing but not entirely fit, Deco's arrival has been critical for Chelsea under first-year coach Felipe Luiz Scolari, who coached him on the Portugal national team.
Deco, 30, has already won UEFA Champion League titles with Porto and Barcelona and could be instrumental in Chelsea's bid for European glory.
Chelsea's ability to hoard talent is why Wigan manager Steve Bruce says the top clubs now dominate the EPL.
"It is getting harder to beat the top teams with each new season," he said. "Chelsea had a bad day today, but then Deco comes along and changes everything with one kick. If it isn't Deco it will be Nicolas Anelka, or Joe Cole, or Florent Malouda, one of them is going to do something special -- and all big clubs have that string of talent."
The next Chelsea signing could be Brazilian Robinho, who has asked out at Real Madrid.
"It would be great if he joined us," Deco said three weeks ago, "and he'd be made very welcome here."
The case against Bruce's argument is the form of the other two big London clubs, Arsenal and Tottenham. Arsenal lost to Fulham, 1-0, while Spurs was upset by Sunderland, 2-1, at home.
Defending champion Manchester United, who opened with a 1-1 draw against Newcastle United, plays Portsmouth on Monday.