Despite a past four-year doping ban, three-time Olympic champion Sun Yang, 33, will compete at China's national swimming championships in Shenzhen this weekend. However, due to Chinese Swimming Association rules, his participation does not qualify him for the upcoming World Championships in Singapore. Sun, who previously served a ban in 2014, will race against rising star Pan Zhanle in multiple freestyle events. This marks the first competitive encounter between the former champion and Pan, who was inspired by Sun. Notably, Zhang Yufei, another prominent Chinese swimmer involved in a past doping controversy, will also compete at the championships.