Swansea striker Bafetimbi Gomis was escorted from the field by medics after he appeared to lose consciousness on the pitch at Tottenham.
The France forward, who has experienced such incidents before in his career, seemed to pass out seven minutes into the game at White Hart Lane, shortly after Nacer Chadli had given Spurs the lead.
Players from both sides were visibly distressed as the medical teams from both clubs sought to revive Gomis, 29.
After a five-minute delay, the player looked to have regained consciousness and he left the field on a stretcher, to the applause of the crowd as well as both teams.
Good news emerged from Swansea at half-time that Gomis was fine and had not been hospitalised.
"He is fine," a Swansea spokesperson said. "He is in the medical room.
"It is something we have been aware of - it is something called a vasovagal condition.
"We have always been aware of it and it has happened before. He has had all the medical and cardiology tests with us."
At White Hart Lane in March 2012, Fabrice Muamba, who was playing for Bolton, suffered cardiac arrest during an FA Cup quarter-final. Muamba recovered in hospital but was unable to resume his playing career.
Gomis had a series of blackouts after joining Lyon in the summer of 2009 and he also fainted while training with France in October of the same year.
At the time, Lyon doctor Emmanuel Ohrant said: “Since 14-years-old, Bafe has been the subject of such vasovagal episodes, comparable to a drop in blood pressure, as a lot of people could experience," said Ohrant.
"At St Etienne, he used to faint. We got his whole medical file, and I can testify very exhaustive medical examinations have been made, and he has been put under extreme monitoring.
"The final conclusion is there is no contraindication to high level sport.
"Finally, I know he is perfectly healthy and he knows it too and we are going on our research.
"We meet heart specialists in Lyon. People are more worried than he is."Reuse content