Somdev had lost to American John Isner in the round of 16 at the Washington ATP 500 event, last week, earning 55 ranking points.
In the doubles, Rohan Bopanna maintained his third rank.
Mahesh Bhupathi's position was unchanged at number seven while Leander Paes lost a place to be 10th.
Left-hander Divij Sharan slid to 72, having lost four positions while his partner Purav Raja gained two places to be 86th on the list.
In the women's rankings, Sania Mirza was static at 19th in the doubles chart.