The idea of human-like robots with artificial intelligence (AI) engaging in sports has been considered in the light of robotics, technology and culture. However, robots with AI can also be used to clarify ethical questions in sports such as boxing with its inherent risks of brain injury and even death.This article develops an innovative way to assess the ethical issues in boxing by using a thought experiment, responding to recent medical data and overall concerns about harms and risks to boxers. (...) The thought experiment imagines a fight between a human and a robot. Critical issues about head trauma and brain injuries are then discussed. These can be summed up in two ethical questions: ‘why is it acceptable for a boxer to deliver concussive and recurrent subconcussive punches to a human head (skull and brain), powerful enough to achieve a knockout, or score more points, or to potentially inflict an injury immediately or eventually resulting in death?’, with the reciprocal question, ‘why is it acceptable to allow oneself to be injured in a like manner, possibly fatally, by an opponent?’The two questions are explored using the thought experiment in two matching perspectives: where the human boxer is attacking and the robot boxer is defending; and conversely, where the human boxer is on the receiving end of punches delivered by the robot. Each perspective opens with some general remarks, followed by an analysis of the boxing contest and eliciting some implications for future opportunities for the sport. (shrink)