Milan attacking midfielder Kaka has not featured for Brazil since their 1-1 draw with Russia back in March.
However, the 31-year-old is enjoying a strong season in his second spell at Milan, scoring four goals in 12 appearances for Massimiliano Allegri's men.
And Marcelo, who played with Kaka during his four-year stint at the Bernabeu, feels the former Ballon d'Or winner could feature in Luiz Felipe Scolari's plans for next year's World Cup.
"Felipe has said the door is always open to players and Kaka is playing very well so he has a chance of going to the World Cup," Marcelo said.
Brazil face Croatia in the opening game of the World Cup on June 12 - a fixture that could pit Marcelo against team-mate Luka Modric - before taking on Mexico and Cameroon.
"Our group is not easy," Marcelo added. "It will be a pleasure to play against Modric."
Brazil could meet Spain in the last 16 if either side fails to top their group, but Marcelo is not thinking about a potential encounter with the world and European champions.
"Spain is the best team in the world and we have a lot of respect for them," he continued.
"But they are not our immediate opponent. There are other very good teams."
