Many of you know Son now as the electric, goalscoring machine for Tottenham Hotspur.
But not so long ago he was an upcoming South Korean talent who was trying to make his name in Europe.
Son dropped out of high school at the age of 16 to sign with Bundesliga club Hamburg SV in 2008 from FC Seoul.
He would make 78 appearances for Hamburg before being bought for a reported €10m by Bayer Leverkusen.
It was at Die Werkself where Donati and Son's career paths crossed, and the former was able to witness the prodigious talent in the flesh.
In an exclusive interview with Donati by Tribalfootball.com, Spurs fans can gain an insight into how Son worked tirelessly on the training field to hone his incredible skills.
"Having played with him is a very nice memory for me, because we were very close friends, a group of young players, with (Karim) Bellarabi too," Donati explained.
"I've always spoken with my friends about Heung-min Son as a predestined and a very professional person. He used to remain to train each day for 10 minutes kicking with the right foot, 10 with the left and 10 on free-kicks.
"He was someone who really devoted himself to daily work with incredible consistency. Watching him scoring penalties in Champions League with the right or the left foot, is not an accident, but, having stayed with him, I can tell it's the result of really much training and sacrifice. Surely he is a very big champion."
And Donati adds that Son could easily make the switch to Serie A in the future due to his admirable work-rate.
"I would see him very well in Italy, because he is one who immediately descends into the new situation.
"He went to England and immediately got settled; he arrived in the Bundesliga and after just a little time he already could speak German: he is a guy who really works hard and if you work, you always get results".