Sindhu was ranked ninth in the world after reaching the finals of the Syed Modi International tournament in January but the defeat to two-time All England champion Shixian Wang of China last week cost her a place as she slipped to the 11th position. She was ranked 10th last week.
Spain's Carolina Marin surged ahead of the 18-year-old Sindhu, reaching the 10th spot, following her semifinal finish at the German Open last month. The list is still headed by Olympic champion Li Xuerui, while Shixian and Yihan Wang are ranked second and third.
National champion Kidambi Srikanth, who stunned world number 10 Tien Ming Nyugen of Vietnam today in the Singapore Open, was static at the 25th spot.
No Indian shuttler could find a place inside the top-25 of the men's, women's and mixed doubles rankings.