New Manchester United midfielder Fred was forced out of Brazil training with an ankle injury on Thursday.
The 25-year-old, who is set to move to United next season after the Premier League club agreed a €55 million deal with Shakhtar Donetsk on Tuesday, was caught by a tackle from Casemiro as Brazil prepare for the World Cup.
Fred tried to remain on the pitch but could not continue and was treated with ice on the sidelines. He sat out for at least the rest of the portion of training in London that was open to the media.
"It is too early to say, we have to see how he develops in the next 24 hours,'' national team doctor Rodrigo Lasmar said of Fred's condition. "He started working out right after. Tomorrow we will know whether he will have to be further examined or not."
There was better news for Brazil, however, as star forward Neymar was added to coach Tite's main formation on Thursday.
Neymar is still recovering from a foot injury that stopped him from playing for three months but now appears set to start Brazil's final pre-World Cup friendly at Austria on Sunday.
The Paris-Saint Germain man came off the bench to score in Brazil's 2-0 win over Croatia on Sunday for his first goal since February.
Midfielder Fernandinho, who started against Croatia last Sunday, was left out to open space for Neymar. Tite also kept winger Willian in the team, which suggests he will use midfielder Philippe Coutinho in a more central position in Vienna.
Brazil players have praised the intense training sessions but critics say Tite's hard-line approach could affect the future of his players in the World Cup.
Midfielder Renato Augusto has been sidelined since last week due to pain in his right knee. Lasmar said Augusto could play on Sunday depending on how his recovery continues this week.
"Everyone wants to fight for a position, our trainings are very strong,'' left-back Marcelo said.
Brazil have until a day before their World Cup opener against Switzerland on June 17 to replace injured players in their 23-man squad.
Brazil's two-week training camp in London ends on Friday, when the team travels to Austria for the friendly.