A group of humanoid robots are undergoing fierce training and systematic upgrading in preparation for a boxing contest to be held on Sunday in Hangzhou, the provincial capital of east China's Zhejiang Province. The boxing event is part of a series of robot competitions jointly sponsored by China Media Group and other institutions. Two humanoid robots, developed by the Hangzhou-based tech startup Unitree Robotics, will be trading punches in a boxing ring during a training session on Tuesday. The fighting robots are more resilient to endure blows as boxing matches are energy consuming and boxers are subject to hard punches.