Arsenal suffered a major injury scare as defender Gabriel limped out of Brazil's friendly win over Senegal at the Emirates Stadium.
The 27-year-old went down just before the hour mark and received treatment to his right thigh before being substituted by manager Carlo Ancelotti.
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"I don't know [if Gabriel has an injury], Ancelotti said post-match.
"I think he felt something in his adductor. He'll be examined tomorrow. We're very sad that he felt that. I wish he gets better soon"
Gabriel's absence would be a major blow for the Gunners after a fine start to the season based on a firm defence that has conceded just five goals in 11 Premier League games.
Chelsea's teenage winger Estêvão opened the scoring for Brazil and Manchester United midfielder Casemiro added the second from a free-kick.
Information from PA and ESPN Brasil contributed to this report.