Daily Chinese Idiom Guessing Game
To be equally matched; to be on a par with each other.
分不出高低好坏。形容水平相当。
唐·陆龟蒙《蠹化》翳叶仰啮，如饥蚕之速，不相上下。”
The two chess players are so evenly matched that their games are always neck-and-neck.