India's Somdev Devvarman slipped 19 places to 89 in the Association of Tennis Professionals (ATP) rankings released on Monday.
Somdev was sidelined for two weeks because of a shoulder injury, which flared up during India's Davis Cup match against Japan.
He is now back in action with the ongoing Malaysian Open.
In the men's doubles, Mahesh Bhupathi and Leander Paes are unchanged at sixth and eighth place and so is Rohan Bopanna at 14.
In the women's singles, Sania Mirza, who is nursing a knee injury, gained two places to 86. She, however, was unchanged in her doubles ranking of 10.