Sergio Aguero was taken to hospital following a heart scare and breathing difficulties during Barcelona’s 1-1 draw with Alaves.
The former Manchester City striker needed medical treatment on the pitch after clutching his chest and complaining of breathing problems.
His heart rate was also racing and he was taken by ambulance to hospital for tests.
Reports in Spain suggest the Argentine striker is “feeling OK”.
Barca interim boss Sergi Barjuan told La Liga TV: “He told me he was a little dizzy.
“I have found out now that they have taken him to the hospital to see what he really has. I do not know any more.”
Barcelona later confirmed: “Aguero reported an episode of chest discomfort and has been transferred to the hospital for a cardiology study.”
Aguero, 33, fell to the ground towards the end of the first half at the Nou Camp and medics rushed to his aid.
He pointed to his chest while he received treatment and teammates checked up on him during worrying scenes.
Medics brought a stretcher onto the pitch, but it was not needed as Aguero soon returned to his feet and walked off the field to be replaced by Philippe Coutinho.
The Argentine striker struggled with Covid-19 after contracting the virus in January this year, missing seven games for City.
And in May last year Aguero said “the majority of players are scared” by the prospect of returning to football too soon amid the coronavirus pandemic.
He said: “The majority of players are scared because they have children and families,
“I’m scared but I’m with my girlfriend here and I’m not going to be in contact with other people. I’m locked in my house and the only person I could infect is my girlfriend.”
The incident comes after Christian Eriksen was fitted with a heart-starter device following his shock cardiac arrest at this summer’s Euros.