Ronaldinho reportedly has a release clause in his contract, but with the value thought to be prohibitively high, a more likely option should he be determined to leave would seem the possibility of invoking article 17 of FIFA's transfer regulations.
This allows players to buy out the remainder of their contract under certain circumstances and would likely prove a cheaper option.
"We are aware of the release clause, but we also know about the existence of article 17. Anything is possible.
"In football, results determine how things go. Barcelona have not won anything since last season and, as Ronaldinho is the star of the team, he is the one who is given the worst criticism."
Assis did not rule out the possibility of Ronaldinho moving to Real Madrid, saying: "It has already happened a number of times, even to big names such as Luis Figo.
"However, I don't like to name specific clubs."
Assis added Ronaldinho could well stay at the Nou Camp should Barca win either the Primera Liga or Champions League title.
He said: "The relationship is strained, but imagine if Barca win the Champions League. They wouldn't let him go if he was a champion, would they?
"With their hands on a title, everything would be different."
