In the second Ashes cricket Test match (2019), Marnus Labuschagne of Australia became the first ever “concussion substitute” player for Steve Smith.
He is also the first ever ‘substitute player’ to bat in a Test innings.
ICC approved such a move in July 2019.
About concussion
A Concussion temporarily affects brain functioning.
Symptoms: Loss of consciousness, memory loss, headaches, difficulty with thinkingand concentration or balance, nausea, blurred vision, sleep disturbances and mood changes.