China's badminton great Lin Dan has quitted matches for seven times since the end of 2010, triggering queries about if this damages the image of badminton and hurts fans.

When being asked about the controversial issue, Paisan Rangsikitpho,deputy president of Badminton World Federation,?said that it's really difficult to judge whether player should quit and what the purpose of the quitting.

"It's really difficult to say you sick or not sick, how can you prove it? we don't like quitting, but we cannot prove, so we cannot accuse someone," said Paisan before Saturday's opening ceremony of the Thomas and Uber Cup held in Wuhan, Hubei Province.

Four-time world champion and Olympic gold medalist Lin retired from the men's singles semifinals against teammate Chen Jin last month at the Asian championships due to waist injury.

Chen moved closer to an Olympic berth by claiming men's singles title at the Asian championships, and finally secured the Olympic ticket at the final Olympic qualifying tournament India Open.

Many had accused Lin of throwing that match in order to help Chen gain valuable qualifying points for the Olympic Games, a charge Lin has vehemently denied.

"We hope player will be professional enough and play for the games. After all, fans are not happy seeing player quit," added Paisan.