"We lost Neymar on that play, and based on what I've seen, I think it's going to be tough for him to play," Brazil coach Luiz Felipe Scolari told reporters.
"He was kneed in his lower back and he was crying out in pain and I can guarantee it won’t be easy for him to recover based on what the doctor told us, and the pain he is in and as it is lower back.
"I don’t know. Let’s hope everything goes well."
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Neymar, who has scored four goals in the tournament to lead Brazil's attack, went down after a challenge by Colombia's Juan Zuniga in the 88th minute and looked to be in pain.
He had to be carried off on a stretcher and was replaced by defender Henrique.
Brazilian television said Neymar was taken straight to hospital without elaborating on the nature of his injury.
Brazil will face Germany in the semi-final in Belo Horizonte on Tuesday without captain Thiago Silva, who was booked on Friday and misses the game through suspension.
Neymar also received support from the country's president, Dilma Rousseff, who tweeted: "Like all Brazil I am one of those cheering from the sidelines for our star Neymar to get better."
Image: Neymar is stretchered off during the closing stages of the quarter-final match against Colombia.
Photograph: Michael Steele/Getty Images
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