Daley Blind considered missing Netherlands' opening game at Euro 2020 after the cardiac arrest his former club team-mate Christian Eriksen suffered on Saturday.
Blind eventually decided to take to the field and broke down in tears after being substituted midway through the second half of the 3-2 win over Ukraine in the Group C match on Sunday.
The 31-year-old, who was diagnosed with heart muscle inflammation in 2019 after suffering a dizzy spell playing for Ajax in a Champions League game against Valencia, spent three years with Eriksen at the Dutch club from 2010 to 2013.
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"[Saturday] had a huge impact on me, never mind the fact that I know Christian well as a friend," Blind said of the incident in Copenhagen where Eriksen collapsed on the pitch during Denmark's match against Finland.
"The situation for him is terrible. Of course, I have also experienced a few things in that area, so that I had to overcome a mental hurdle to play."
Blind was fitted with a pacemaker that treats dangerously abnormal heart rhythms but it failed while he was playing in a friendly last August and he collapsed again - although it was later described as a one-off incident.
"I had to persuade myself to play but I'm proud that I did and that's why my emotion came bursting out at the end of the game," he added.
"I definitely thought about not taking part. The images on television and the incident had a big impact and I didn't sleep very well because of them. I really had to overcome a big hurdle to do this."
News that Eriksen was awake and talking in hospital came as a relief.
"If it didn't go well, it would have haunted my head even more. When Christian encouraged his own team-mates to play is when I decided to play myself. Also because I'm safe, according to the doctors," Blind said.
Dutch coach Frank de Boer cancelled a team meeting on the eve of the game because of the distress among the Dutch players.
Denmark team doctor Morten Boesen says Eriksen was "gone" after a cardiac arrest but medical test results have been normal so far.
Eriksen is currently being treated at Rigshospitalet, one of Denmark's top hospitals, which is less than a mile from Parken Stadium in Copenhagen.
"The exams that have been done so far look fine," Boesen told a news conference.
When asked what caused the incident, Boesen said: "We don't have an explanation why it happened. I can't answer that question.
"I didn't see it live, I saw it on screen when it happened. You saw the same as me. No explanation so far."
Boesen confirmed Eriksen suffered a cardiac arrest, saying: "He was gone.
"We did cardiac resuscitation, it was a cardiac arrest.
"How close were we to losing him? I don't know, but we got him back after one defib, so that's quite fast."