Sergio Aguero suffered breathing difficulties on his home debut for Barcelona and has since been whisked off to hospital for further tests.
The Argentine striker, who left Manchester City for Barcelona as a free agent in the summer, required medical attention shortly before half-time having complained of dizziness.
There was growing distress in the stadium in the 40th minute as Aguero lay flat on pitch, having gone down moments after he had his hand placed on his chest.
The 33-year-old was then replaced by Philippe Coutinho and he has now gone on to hospital for some precautionary tests to understand why he found himself struggling to breathe.
Read more: Strange how many super-fit sports people suddenly have breathing and heart problems during games – Barcelona striker Sergio Aguero is taken to hospital for heart tests after struggling with breathing and needing on-pitch treatment before being replaced during his home debut