Indian badminton ace Pulella Gopichand has called for world rankings protection to help players making their comeback from injury.

Gopichand, All England champion in 2001, missed the world championships which end in Birmingham, England, on Sunday after knee surgery last November, although he resumed training in May.

The 29-year-old, among the top 10 two years ago, has slipped to 121 in an injury-plagued career and failed to make the men's singles competition because he was ranked too low.

"If you are out for four or five months the entire scenario changes. There should be some protection, (some) stabilisation," he said.

Other top names to have been affected include former world number one Peter Gade of Denmark and Indonesia's H. Hendrawan, world title winner in 2001. Gade was handed a wild card to the Birmingham world championships only to lose in the first round.

Tennis has a system of protecting rankings for six months and a spokeswoman for the International Badminton Federation said they were aware of the problem.

However, the issue cannot be addressed until after next year's Athens Olympics. The sport is in a year-long qualifying period where final rankings decide who is eligible for the Games and the system cannot be altered in the meantime.