Belgian footballer Gregory Mertens was in a critical state in hospital on Tuesday after suffering a heart-attack playing for Lokeren reserves the previous night, press reports said.
The 24-year-old defender collapsed on the field 20 minutes into the game against Genk and was given emergency treatment before being rushed to hospital.
The reports said that Mertens had been placed in an induced coma in an effort to save his life.
"Sporting Lokeren sympathises with the family and hopes for a positive outcome," his club said in a statement.
Mertens began his career in Brussels with Anderlecht, but moved to Bruges in 2011 before transferring to Lokeren in January, 2014. He was capped several times for Belgian national youth sides.
(For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)