On Sunday, Denmark's team doctor said Christian Eriksen said he "was gone" before being resuscitated from cardiac arrest.

Christian Eriksen suffered a cardiac arrest when he collapsed in Denmark's Euro 2020 match against Finland, said Danish team doctor Morten Boesen.

Earlier, officials said the midfielder was stable in hospital and had sent his greetings to his national teammates. Eriksen collapsed shortly before half-time in Denmark's opening Euro 2020 game against Finland on Saturday.

Denmark's players gather as paramedics attend to midfielder Christian Eriksen (not seen) during Saturday's match. Photo: CNN

"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. However, we don't have an explanation as to why it happened."

According to the BBC, 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 hospitalized 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 teammates.

"The team and staff of the national team have 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."

Christian Eriksen is pictured during Saturday's match between Denmark and Finland, shortly before he collapsed. Photo: CNN

His distressed teammates surrounded him, and the shocked supporters at Parken Stadium were visibly upset as the player was treated. Boesen said Eriksen was unconscious when he reached the player on the pitch.

"When I got to him, he was on his side, he was breathing, I could feel a pulse, but suddenly that changed, and we started to give him CPR," he said.

"The help came really fast from the medical team and the rest of the staff with their co-operation, and we did what we had to do and managed to get Christian back."

'Christian Eriksen, I love you'

After he collapsed, Eriksen's Danish teammates formed a wall around him to protect the Inter Milan star from view as he was receiving treatment. Players from both teams and fans in the stadium were visibly distressed as Eriksen was being attended to by medics.

Fans were visibly upset as Eriksen received treatment on the pitch. Photo: Getty Images

In Group B's other match, Romelu Lukaku opened the scoring for Belgium over Russia and ran over to the camera to send support to his Inter teammate. "Chris, Chris, sterkte jongen (Dutch for 'wish you strength/all the best'). I love you!" he said.

Lukaku, who scored a second goal late in the game, told journalists in his post-match interview that he "cried a lot" and "was scared" when he first heard the news of Eriksen's collapse, CNN reported.

"I spend more time with him than with my family, so my thoughts are with him, his girlfriend, his two kids, and his family," he added.

In Goyang, South Korea, Eriksen's former teammate Son Heung-Min scored a goal in his 2-1 victory over Lebanon in a World Cup qualifier. It shouted, "Christian Eriksen, I love you," according to a tweet from his club Tottenham.

Other goodwill messages from around the world flooded social media. Harry Kane, the England captain and former teammate of Eriksen, sent his love to the Danish talisman and his family in a tweet Saturday.

"Stay strong, mate," said Kane, who will be playing in his first game of Euro 2020 Sunday afternoon.

The Duke and Duchess of Cambridge paid tribute to the medics who ran onto the pitch to help Eriksen and referee Anthony Taylor, who immediately stopped the game.

"Encouraging news about Christian Eriksen, we are all thinking about him and his family. Well done to the medical team and Anthony Taylor for their calm and swift action," said a tweet from the royals' official Twitter account, signed off "W."

Chau Polly