Ronaldo is considered as one of the best footballers of all-time during his distinguished career.
Martinelli joined Arsenal in the summer from Ituano, a club which plays in the lower tiers of Brazilian football.
The 18-year-old has already scored 10 goals in all competitions for the Gunners, becoming the first teenager to do so for the North Londoners since Nicholas Anelka in 1998-1999 season.
Ronaldinho has insisted he sees shades of Ronaldo in Martinelli, and has tipped the youngster to break into the Brazil national team very soon.
“We as Brazilians are very excited about him and his future. It is one thing to have the talent - but another at the age of 18 to have the confidence," the Brazilian told the Mirror.
“He reminds me of Ronaldo in his first season in Europe he scored 30 goals and people were thinking: ‘who is this 18-year-old Brazilian kid?’
“He 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.”
“I am sure that his first Brazil cap is very close - he is ready," he added
