Belgian defender Gregory Mertens died on Thursday, three days after collapsing while playing for Lokeren's reserve side.
Mertens suffered heart failure on the pitch and received CPR before being transported to a hospital in Genk, where he was placed in an induced coma.
Lokeren confirmed the 24-year-old died on Thursday afternoon.
The club said doctors tried to operate on the player on Tuesday, but there were more complications.
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BRUSSELS -- Lokeren defender Gregory Mertens remained in critical condition on Wednesday, two days after he suffered heart failure during a training match.
The 24-year-old player in Belgium's top division collapsed early in Monday's game, and has been kept in a coma as doctors continue to give him emergency treatment.
Lokeren defender Gregory Mertens is in a critical condition after suffered a suspected cardiac arrest during a match.
Former Belgium under-21 international Mertens was representing Lokeren's reserve side in a game against Genk on Monday when he collapsed and received CPR on the pitch.