The Atletico Mineiro attacker is hopeful that a run of good form will see him win coach Luiz Felipe Scolari's trust ahead of next summer's tournament
The 33-year-old last featured for the Selecao in the April friendly against Chile, but believes that his good relationship with coach Luiz Felipe Scolari could see him get a call-up ahead of the tournament.
"He is a very direct person and is always open with me. I know that there are still opportunities available for those who are playing well," he told Fifa's official site.
"He seems to have the core of his squad decided, but whoever is in good form at the right time will go too.
"I'm always working hard to improve. If there is a chance of playing in the World Cup, I'll be ready, and I'll be at my peak. My goal is to always be at my best.
"It was great to be back with the national squad [earlier this year]. Luiz Felipe Scolari and I have won so much together and we have a good relationship."
Ronaldinho's contract at Atletico Mineiro expires at the end of December.