The gifted 18-year-old forward, who turned down a 20 million euro move to Chelsea and made his Brazil debut in August, had been in danger of spoiling his image as a smiling, carefree youngster brimming with talent on the pitch and relaxed off it.
Last Sunday, he sparked a free-for-all at the end of Santos' 2-1 away loss to Ceara after berating a rival defender for his rough marking. Police had to separate the players.
He also chastised captain Edu Dracena and coach Dorival Junior after Edu chose another player to take a penalty in Santos' 4-2 home win over Atletico Goianiense on Wednesday.
Fined by Santos and criticised publicly by his team mates after his heated exchange with Edu and Dorival, he made an emotional statement on Thursday to try to erase the bad impression.
"I'm here to say more than sorry and (I expect) no pardon. I got home and saw what I'd done," Neymar told reporters while holding back tears. "I acted wrongly, I left even my father and mother shocked... I'm ashamed of what happened.
"I say sorry to Dorival, sorry to Edu, who is the team captain, and to my team mates. I apologise to... kids who look up to Neymar. Forgive me for what I did."
Possibly a mere coincidence, the behaviour of one of Brazilian football's biggest jewels began after he turned Chelsea down to sign a new five-year contract with Santos.
In the first half of the year, he shared the limelight with the on loan Robinho and fellow youngster Paulo Henrique Ganso as part of a brilliant trio that inspired Santos to the Paulista (Sao Paulo) state championship and the Copa Brasil.
Now, Robinho has left for AC Milan and Ganso is out until next year through injury.
Santos said they would help Neymar in whatever way they could but at the same time expected a professional attitude from him.
"The club will demand deep changes in his behaviour on and off the field, with his colleagues and opponents and will support the player so this moment of difficulty can be overcome," they said in a statement.
Seen as a key component for the future of the Brazil side that will host the 2014 World Cup, Neymar's behaviour has been closely watched by national team coach Mano Menezes, who expressed his concern.
"He needs to know how to behave as a stand-out player in Brazilian football and later out there in world football," Menezes told TV Globo.
"If we allow these (things) to happen with such frequency in his club, in no time it will get transferred to the Brazil team."
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