Cameroon international, Patrick Ekeng Ekeng has died after an on-field collapse in a Romania Liga game, doctors said.
The 26 year old was on the pitch for only seven minutes after coming on in the second-half as a substitute.
He fell to the ground at a time his side was winning 3-2 against Viitorul Constanta.
Reports suggest no professional first aid given at the stadium after the suspected heart attack.
The game, which was live on TV, was stopped and Ekeng was immediately taken to the hospital. Dozens of fans gathered outside the stadium in solidarity.
Ekeng signed for Dinamo in January and had impressed in his appearances for the club.
Previously, Ekeng played for Cordoba CF, Swiss club Lausanne, and French club Le Mans. He moved to Dinamo last year.