Somdev, who touched a career-best 63rd earlier this month, took a break from the circuit after Wimbledon and since then losing points.
In the ATP doubles ranking, there was no change in the rankings of Mahesh Bhupathi (5), Leander Paes (8) and Rohan Bopanna (10).
The pair of Paes and Bhupathi is at number four in the team ranking, while Bopanna and Aisam-ul-haq Qureshi remained at number six.
In the WTA ranking, Sania Mirza slid to 64th from 63rd in singles, but maintained her 11th position in the doubles.
Her team ranking with Russian Elena Vesnina is also intact at number two in race to year-end championship.
Sania-Elena pair have 4506 points in the list, headed by Kveta Peschke and Katarina Srebotnik, who have 6865 points. The top-four pairs compete in the prestigious year-end championship.