Christian Eriksen suffered a cardiac arrest when he collapsed in Denmark’s Euro 2020 match against Finland, said Danish team doctor Morten Boesen, the BBC reports.
Earlier, officials said the midfielder was stable in hospital and had sent his greetings to his national team-mates.
Eriksen collapsed shortly before half-time in Denmark’s opening Euro 2020 game against Finland on Saturday.
“He was gone. We did cardiac resuscitation, it was a cardiac arrest,” said Boesen.
“How close were we to losing him? I don’t know, but we got him back after one defib [defibrillation] so that’s quite fast.
“The examinations that have been done so far look fine. We don’t have an explanation to why it happened.”
The 29-year-old Inter Milan player had emergency medical treatment on the pitch before being taken to hospital.
“His condition is stable and he continues to be hospitalised for further examination,” said a statement from Danish officials on Sunday morning.
“This morning we have spoken to Christian, who has sent his greetings to his team-mates.
“The team and staff of the national team has received crisis assistance and will continue to be there for each other after yesterday’s incident.
“We would like to thank everyone for their heartfelt greetings.”
Head coach Kasper Hjulmand said Eriksen told him he did not remember much from Saturday’s collapse.
He quoted the midfielder as saying: “I think you are feeling worse than I am. I feel as if I’m about to go training now, boys.”
Hjulmand added: “Christian is in good spirits and it’s a huge relief for the players after all this uncertainty. There is no doubt that we have been on the ropes.”