On Tuesday night, Annu made a good start with a throw of 59.25m, finishing five out of all 12 athletes in her first attempt.
The 27-year-old, who is the first Indian to reach the finals of the women's javelin throw, improved her performance in her second attempt with a better throw of 61.12m but slipped two places to seventh. However. in her third effort, she couldn't eclipse her previous throw and recorded a distance of 60.20m to stay at the seventh spot.
Thereafter, her fourth attempt was 60.40m which took her to the eight spot. Her 5th throw was just 58.49m and in her last and final attempt, she came up with a 57.93m throw to finish at the eighth spot with a best throw of 61.12 m.
Australia's Kelsey-Lee Barber won the gold medal with her final attempt of 66.56m while China's Shiying Liu and Huihui Lyu bagged the silver and bronze medals, respectively.
On Monday, Annu had created history by becoming the first Indian woman to reach the javelin final.
Annu bettered her own national record of 62.34m set in March during the Federation Cup in Patiala by throwing the javelin to a distance of 62.43m.
Meanwhile, India's Avinash Sable also managed to make a cut in the finals of the men's 3000m Steeplechase after India lodged a protest against the two incidents which took place during the race.
Sable, who broke his own national record and finished 7th in the third heat, fell twice during the race for no fault of his own as the reigning junior world champion Takele Nigate of Ethiopia running in front of him tripped and fell and thus the hopes of Sable making to the finals were dented.
The 24-year-old Indian clocked eight minute 25.23 seconds to finish 20th overall out of 44 athletes who completed the race.
However, after the protest lodged by the Athletics Federation of India, Sable was added as the 16th competitor for the final race to be run on Friday.
( With inputs from IANS )