Much like how Ronaldo burst onto the European scene as a teenager with PSV Eindhoven in 1994, Ronaldinho believes his compatriot has the potential to be among the world's best.
Speaking to The Mirror, the FC Barcelona legend said: "He [Martinelli] reminds me of Ronaldo his first season in Europe he scored 30 goals and people were thinking: 'who is this 18-year-old Brazilian kid?"
"It is one thing to have the talent – but another at the age of 18 to have the confidence.
"He [Ronaldo] wanted the ball, he would run at players, there was no fear no matter what players or team he was playing against – and I see that similar attitude in Martinelli.
"He just wants to be on the ball and score goals. Ronaldo went on to be the best player in the world – and that can also be the aim of Martinelli."