Sergio Aguero was taken to hospital after complaining of dizziness during the first half of Barcelona's 1-1 draw with Alaves on Saturday, interim head coach Sergi Barjuan confirmed.
The Argentine was absent for the first two months of the season as he recovered from a nagging calf injury, finally making his club debut in mid-October against Valencia.
But he was in clear discomfort on the pitch before coming off late in the first half, later leaving the stadium as a precautionary measure.
What happened?
Almost 40 minutes were on the clock at Camp Nou when Aguero pulled up in discomfort.