The Arsenal youngster, who was signed in the summer from Brazilian side Ituano, has caught the eye with an impressive first season in English football.
Martinelli scored a brilliant breakaway goal against Chelsea last week; announcing himself against a top side.
By doing so, he became the first teenager to reach double figures in a single season for Arsenal since Nicolas Anelka.
Martinelli isn't just exciting Arsenal fans, but also ex-players such as World Cup-winning Brazil legend Ronaldinho.
Ronaldinho has come out full of praise for the young Gunner, comparing his rise to that of Ronaldinho's former international teammate Ronaldo.
"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," Ronaldinho told the Mirror.
"He 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?'
"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."
Martinelli will be hoping to continue his fine form as Arsenal prepare to face Bournemouth in the FA Cup fourth round on Monday night.
Ronaldinho has also stated that the 18-year-old can look forward to his first senior international cap for Brazil before long.
"I am sure that his first Brazil cap is very close - he is ready. Historically the national team has never been concerned with age," he added.
"Ronaldo was playing for Brazil at 17 - and more recently Neymar and Jesus have played an important role when they were only teenagers.
"If you have the ability and the talent then you will get the chance - and the world can see that he (Martinelli) has the talent."
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