Former Chelsea midfielder Oscar was rushed to hospital on Tuesday after collapsing during training.
The 34-year-old is now considering retiring from football, according to the UK Metro.
The incident occurred at São Paulo’s training ground after the player fell ill during pre-season medical tests.
He reportedly fell to the ground and was unconscious for up to two minutes.
Oscar was taken to the Albert Einstein Israelite Hospital with suspected cardiac issues.
He is believed to be in a stable condition and is undergoing several heart checks.
Oscar has an 11-year-old daughter and an eight-year-old son with his wife, Ludmila, who is currently pregnant with their third child.