Lower-league footballer Tim Nicot has become the second Belgian player to die of cardiac arrest in the past two weeks.
The 23-year-old left-back for fourth-tier Wilrijk-Beerschot was playing in a tournament in Hemiksem when he collapsed on Friday.
He was placed in an induced coma and his club confirmed his death on Monday.
In late April, Lokeren defender Gregory Mertens, 24, died after collapsing during a reserve game.
A club statement said Nicot "fought like a bear" and was the "idol of our supporters".
It described him as "always in a good mood, always making time for an umpteenth selfie with a fan".
Three years ago Bolton midfielder Fabrice Muamba, then 23, suffered a cardiac arrest in an FA Cup game with Tottenham. He was "in effect dead" for 78 minutes but survived, although he never played again.
Nicot's team-mate Wesley Snoeys said: "So many questions. Always the same question comes up: why why why? You left us far too soon. I will never forget you. Forever in my heart."
Jef Snyders, another Wilrijk-Beerschot player, added: "Football will never be the same anymore. Rest in peace mate."