Pechonkina only returned from a year's lay-off in early July
Women's world 400m hurdles record holder Yuliya Pechonkina has pulled out of the World Athletics Championships in Berlin due to sinusitis.
She also missed the Beijing Olympics last summer due to the same problem.
Pechonkina, 31, who ran 52.34 seconds in 2003 to set her world mark, won the world title in Helsinki in 2005.
Australian Jana Pittman-Rawlinson - the 2007 400m hurdle winner - will miss Berlin, while London marathon champion Irina Mikitenko has also withdrawn.
The 26-year-old Pittman-Rawlinson pulled in July due to a back-related injury, while Mikitenko, who was the winner in London for the last two years, was worried by by her poor form after her father's death two weeks ago.
"Irina Mikitenko's withdrawal is a blow for our team," said German federation sports director Jurgen Mallow.
"Irina did not manage to hit World Championship form in the St Moritz altitude training camp. We are very, very sad about this."
The World Championships begin on Saturday, 15 August.