Sergio Aguero was taken to hospital for tests after suffering “chest discomfort” as Barcelona drew against Alaves in their first match since the sacking of Ronald Koeman.
Aguero went down clutching the top of his chest and received treatment for several minutes before being helped off the pitch just before half-time.
Barcelona later said he was admitted to hospital to have a “cardiac exam”.
Luis Rioja earned Alaves a point after Memphis Depay’s opening curling effort.
Former Manchester City striker Aguero, 33, was taken away in an ambulance and Barca interim boss Sergi Barjuan told La Liga TV: “I can’t tell you much more. I know he has been taken to a hospital and they are having tests done.”
The point against Alaves keeps Barcelona in ninth place – eight points behind La Liga leaders Real Madrid, who edged Elche 2-1 earlier on Saturday.