The tricky attacker stated earlier this week that he does not have a preference between the Catalan powerhouse and Real Madrid, but his compatriot has little doubt that he will eventually end up at Camp Nou.
"I have spoken with him. He should have left Brazil already in my opinion. I believe that Barcelona has a 90 percent chance of signing him," Roberto Carlos told Al Jazeera.
The 39-year-old then went on to dismiss suggestions that the attacker might not be compatible with Lionel Messi.
"He is able to adapt to any situation," he insisted.
Neymar has a contract with Santos until the summer of 2014.