Sergio Aguero reportedly fainted during half-time and was taken to hospital as Nigeria stunned Argentina in a friendly.
The Manchester City striker fell ill in the changing room. He was replaced by Dario Benedetto.
Aguero had earlier scored to put his side 2-0 up, becoming the Albiceleste's third-highest scorer in the process.
But he suffered health issues at the break and was forced to leave the Stadion FK in Krasnodar to be given medical attention.
Aguero underwent tests in hospital as Nigeria came back to record a famous 4-2 win