Neymar was in tears as he left the field with a left knee injury at the end of the first half of Brazil's 2-0 World Cup qualifying loss at Uruguay on Tuesday.
The 31-year-old striker tripped and fell during a run in the 44th minute at the Centenario Stadium and was immediately surrounded by players from both teams as he held his knee.
Neymar was carried off on a stretcher with both of his hands on his face. Richarlison came on to replace him.
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Neymar used crutches as he left the stadium. Brazil's doctor Rodrigo Lasmar told reporters it was too early to determine the severity of Neymar's injury.
“We did all the tests and we will repeat them tomorrow. Those 24 hours are key to see how his knee will respond, how swollen it will be and what images will show,” Lasmar said. “Let's wait for the exams with calmness, evaluate with calmness and tell you once we have a diagnosis.”
Uruguay led 1-0 when Neymar was hurt. Brazil went on to suffer its first loss in 37 matches in World Cup qualifying.
Neymar did not speak to reporters in Montevideo. After leaving the stadium, he posted on Instagram that “God knows about all things.”
“All the honor and all the glory will always be yours, my Lord. No matter what, I have faith,” he said in the post.
Neymar, who plays for Al Hilal of the Saudi Pro League, was criticized by fans before the World Cup qualifier because of his subpar performance during Thursday's 1-1 draw between host Brazil and Venezuela. He recently returned to play after a right ankle injury that sidelined him for almost six months.
Neymar made his national team debut in 2010 and has 79 goals in 128 appearances for Brazil.