We present a case of cardiac concussion (commotio cordis) resulting from blunt chest trauma injury in a professional athlete. The soccer player received frontal injury to the chest caused by another player’s knee during a training session. A few minutes of spontaneously relapsing unconsciousness ensued and the patient was admitted urgently for observation. Surface electrocardiogram showed dynamic alterations in the precordial leads, cardiac necrotic markers were only mildly elevated and cardiac magnetic resonance could not detect any injury‑related pathology. The athlete received conservative treatment. We discuss the differential diagnosis with cardiac contusion and Brugada syndrome. Electrocardiographic abnormalities persisted during the two‑week follow‑up. The patient successfully continues his professional soccer career