World number one Lee Chong Wei has been provisionally suspended for an "apparent" anti-doping violation.
The Badminton World Federation (BWF) said he was banned because of "an adverse analytical finding of a sample taken at the World Championships".
The 32-year-old Malaysian, who tested positive for the banned anti-inflammatory agent dexamethasone, faces a two-year ban if guilty of doping.
He could also lose the silver medal he won at August's World Championships.
Lee has posted messages on his Twitter and Facebook accounts denying using drugs to gain an advantage.
"There are so many unanswered questions and I hope to clear my name soon," he wrote. "I never cheated nor will I ever rely on banned substances."