Brazil's number 10 suffered a bad-looking ankle injury in their 2-0 win over Serbia on Thursday.
Neymar was taken off with ten minutes remaining after suffering nine fouls against the Serbians, the most on any player in Qatar so far.
The Paris Saint Germain superstar might have feared the worst when he was substituted, re-echoing memories of that back injury he sustained against Colombia in the quarterfinals of the 2014 World Cup which ruled him out of the rest of the tournament.
The prognosis of Neymar's latest setback suggests he will be back if the Selecao reach the knockout rounds as expected and he has promised to come back stronger for the run-in.
"The pride and love I feel for wearing the shirt has no explanation," he wrote on Instagram. "If God gave me the opportunity to choose a country to be born, it would be BRAZIL.
"Nothing in my life was given or easy. I always had to chase my dreams and my goals. Never wishing evil on anyone but helping those in need.
"Today has become one of the hardest moments in my career... and again in a World Cup. I have an injury yes, it's annoying, it's going to hurt but I'm sure I'll have the chance to come back because I will do my best to help my country, my team-mates and myself."
Neymar added: "Wait a long time for the enemy to knock me down like this? NEVER! I am a CHILD OF THE IMPOSSIBLE GOD and my FAITH is endless."
Brazil will face Switzerland and Cameroon in their remaining group stage games.
