Moussa Dembele withdrew from Atletico Madrid training on Tuesday after fainting.
Atletico's medical staff urged to attend to the French forward, but Dembele managed to get up without needing any further help.
According to sources at Atletico, Dembele had "a slight drop in blood pressure" that caused him to faint and subsequently withdraw from the session, reports Marca.
The 24-year-old forward will undergo medical exams and as Atletico stressed, he is under "observation and has absolutely normal vital signs".
Tuesday's session was open to the media who were about to depart when the incident took place.