"We are happy because we know that after a big game like Chelsea some teams can relax a little bit but the team showed a lot of determination to keep going," the Brazilian told the club's official website.
"It was a difficult game because Portsmouth came here to just defend and tried to play on the counter-attack, but we were patient and had a lot of possession so I think we deserved the win.
"It is good to be three points clear at the top, but we know that we cannot think about this win too much.
"We have to keep up the hard work and we have to keep thinking game by game. We know how difficult it is to win the Premier League, but we have to keep going."