Brazil captain Neymar suffered a sprained ankle in his team's World Cup win over Serbia on Thursday and faces a medical assessment in the next 48 hours, the national team doctor said after the match.
The Paris Saint-Germain star suffered the injury in the 2-0 victory against Serbia on Thursday when he collided with Nikola Milenkovic during the second half.
The 30-year-old tried to continue but was substituted with about 10 minutes to go and underwent an examination on Friday.
Rodrigo Lasmar, the doctor for the Brazilian football federation (CBF), said the 30-year-old had suffered "ligament damage" and would miss the match against Switzerland on Monday.
Brazil right-back Danilo will also miss the second Group G game with an ankle strain.
"We will not have these two players for our next match but they continue their treatment with the aim of recovering in time for the rest of the competition," the doctor said in a video released by the CBF.
Coach Tite was optimistic after the Serbia match that Neymar would be back to lead Brazil's bid for a record-extending sixth World Cup crown.
"You can be certain that Neymar is going to play in the World Cup," Tite said, adding that the attacker had initially stayed on the pitch after hurting his ankle "because the team needed him".
Neymar's career has been peppered by injuries which have impacted on his previous two World Cups.
In 2014 he suffered a fractured bone in his back in the quarter-final win over Colombia, meaning he was sidelined when the hosts were thrashed 7-1 by Germany in the semi-finals.
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