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.
Brazil manager Tite remained optimistic afterwards that Neymar will still have some part to play in the quest for a sixth world crown, telling reporters: "[Neymar] felt this pain throughout the game, but he decided to stay on the pitch to help his team."
"So it's remarkable that he could bear this pain while his team was playing. He stayed 11 minutes on the pitch after his injury, until the moment he could no longer continue, and he was substituted.
"We are confident that Neymar will continue playing; he will continue playing in the World Cup.
"I didn't see Neymar was injured – the capacity he had to overcome it tricked me, I only saw it now in the video. When he actually dribbled, it caused that injury, and in that second goal you see when he controlled the ball that he felt it."
It has now been confirmed that Neymar and right back Danilo, who also suffered an ankle injury in the same game, will miss upcoming games against Switzerland and Cameroon.
"Neymar and Danilo went through a MRI on Friday afternoon and we found ligament damage in the ankle of both of them," said Brazil team doctor Rodrigo Lasmar.
"It is important to be calm and evaluate day by day. The idea is to recover them for the rest of the competition."
