Brazil's next match is Monday against Switzerland. The five-time world champions end their group-stage campaign against Cameroon on Dec. 2. Brazil leads Group G along with Switzerland, which opened with a win against Cameroon.
If Neymar can't play, his replacement would likely be Rodrygo, who came in as a second-half substitute against Serbia on Thursday.
The 30-year-old Neymar was also hurt at the 2014 World Cup in Brazil, when his tournament ended with a back injury in the quarterfinals against Colombia. He had to be taken off the field on a stretcher, and Brazil ended up losing to Germany 7-1 in the semifinals.
Neymar's right foot has caused him problems in the past, being among the series of injuries he suffered since the 2018 World Cup in Russia. Another right ankle sprain led him to miss the 2019 Copa America that Brazil won.
The 30-year-old Neymar has yet to win a major title with the national team. He helped the "Selecao" win the 2013 Confederations Cup and its first Olympic gold medal at the 2016 Rio de Janeiro Games.
With 75 goals for the national team, he is two shy of Pele's scoring record.
Another player with a sprained right ankle on Thursday was defender Danilo, though Lasmar said his injury was not serious.
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