Sergio Aguero was taken to hospital after fainting in the dressing room at half-time in Argentina’s 4-2 defeat by Nigeria in Krasnodar, Russia.
The Manchester City striker had scored to put his side 2-0 up in the first half, but Arsenal’s Alex Iwobi found the net twice as Nigeria came back.
The Argentina FA said the 29-year-old had been taken to hospital to “carry out routine studies as a precaution”.
“He got dizzy and had to leave,” Argentina manager Jorge Sampaoli said.
Aguero, who became City’s all-time leading goalscorer earlier this month, had recently returned to action after he suffered a rib injury in a car crash in Amsterdam in September. He was injured when a taxi he was travelling in after attending a concert crashed into a lamp post.
In Wednesday’s international friendly, Leicester’s Kelechi Iheanacho netted with a free-kick and Brian Idowu was also on the scoresheet for the Super Eagles, who had fallen behind to strikes from Aguero and Ever Banega.