Kylian Mbappé was sidelined from Real Madrid's Club World Cup match due to his hospitalization for acute gastroenteritis, and the superstar's return date uncertain.

Real Madrid says forward Kylian Mbappe has been hospitalized with an acute case of gastroenteritis. World Cup winner Mbappe missed Madrid’s opening game at the Club World Cup against Saudi Arabian team Al Hilal in Miami on Wednesday because of a fever.

His illness casts doubt over what part he might be able to play in the monthlong tournament in the United States, with Madrid facing Pachuca in Charlotte, N.C., on Sunday.