Gaeei, who was 15 years old back then, and a friend of his had taken part in a New Year's race when his father, waiting to greet them at the finish line, fell over and hit his head hard on the asphalt.
"I don't really remember it. Apart from the fact that I, of course, saw it happen," says the Ajax profile to bt.dk
His father had suffered a cardiac arrest and was dead for ten minutes before being revived.
"It wasn't even because he had smoked or anything. It was some calcification, and it took two days before he woke up again – and I am eternally grateful for that," explains Gaaei.
The dreadful experience had a severe impact on the Danish defender, who has worked to see a psychologist to mend the mental repercussions after the experience.
However, the experience has also taught him about life and the fact that there are some things that are more important than football.
"It was a tough period. I was 15 at the time, and it showed me that there is more to my life than just football.
"Of course it (football, ed.) is my whole life, but in the end, life is more important. It dawned on me that day. At the same time, it has also helped to make me strong mentally, and I got through it at such a young age," says the now 22-year-old right-back.
Eight years later, Gaaei's father is still safe and sound and hasn't experienced any side effects since the experience.
After a very successful year personally for Gaeei, during which he has grown to become one of the main profiles in the Ajax team, Gaeei has been selected for the Danish national team, which will face Northern Ireland in a friendly at the Parken stadium in Copenhagen on Saturday night.