Such a difficult task definitely requires advance preparation. Many medical students start looking for mentors in clinical settings early on for this reason. Those who aim to pursue a doctorate often start by finding a doctoral advisor during their master's, so they won't have to find another advisor for their doctorate, and it helps maintain continuity in their research for publishing papers.
Speaking of Cao Zhao, he was just promoted to doctoral advisor two years ago. Those capable of being a doctoral advisor can, of course, be a master's advisor as well. He admitted his first clinical doctoral student last year, Student Duan Sanbao. Whether he has quotas for this year's admissions is unclear until the school makes their decision.
