The World Cup winner featured for 78 minutes of Argentina's 1-0 friendly victory against Venezuela at the Hard Rock Stadium in Miami on Sunday.
According to a statement from the Argentina national team's official X account, the feisty midfielder has been diagnosed with synovitis in his right knee following the clash.
The Argentine has returned to Cobham, but it is unclear what the extent of his injury is, adding further woes to a team that is already without a number of key players this season.
Chelsea are already without Andrey Santos, Cole Palmer, Liam Delap through various injuries, with Willian Estevao, Tosin Adarabioyo and Wesley Fofana also doubtful ahead of the next Premier League fixture against Nottingham Forest.
The 24-year-old club vice-captain has featured in ten matches under manager Enzo Maresca this season, impressing with three goals and an assist in all competitions.
Harry Kane, Lamine Yamal and Kylian Mbappe headline the 30-player shortlist for the 2026 Ballon d'Or, with the winner to be announced at the ceremony in London on October 26.
Manchester United have reportedly decided against bringing David Alaba to Old Trafford, despite the Austrian defender being available as a free agent.
Liverpool midfielder Alexis Mac Allister has admitted he was "very, very sad" after being told the club was not in a position to offer him a new contract.
Manchester United supporters have been urged to come together for a peaceful demonstration before Sunday's derby against Manchester City at Old Trafford.
