Some of the world’s most famous tennis players are distraught by the disappearance of colleague Peng Shuai and are challenging China’s Communist Party to get answers. So far it’s a standoff with little visible impact as tennis players like Roger Federer and Rafael Nadal — joined by tennis governing bodies, human rights groups, and at least one athletes’ lobby — try to turn their profiles into power. Peng disappeared after making allegations two weeks ago of sexual assault against former vice premier Zhang Gaoli who was a member of the all-powerful Politburo Standing Committee and a lieutenant of General Secretary Xi Jinping.