Cape Town - South Africa's top-ranked men's tennis player Kevin Anderson has slipped down the global rankings, after failing to defend his Delray Beach title over the weekend.
Anderson dropped eight places to 37th in the latest ATP list released on Monday, having started the year ranked one place higher, in 36th.
The South African lost 6-2, 7-6 (7/1) to American John Isner in the quarter-finals of the Delray Beach Open - reversing the result which Anderson had achieved on the way to winning his second ATP title last year.
In contrast, fellow South African Izak van der Merwe moved into the top 250 players worldwide, climbing four spots to 249th.
Meanwhile, in the women's rankings, South Africa's No 1 Chanelle Scheepers was unchanged at 60th in the latest WTA rankings on Monday.
Scheepers has remained constant this year, having started 2013 in 60th. She has not moved since the first rankings were released on Febuary 7.
Kevin Anderson (37)
Izak van der Merwe (249)
Rik De Voest (313)
Fritz Wolmarans (329)
Ruan Roelofse (522)
Chanelle Scheepers (60)
Chanel Simmonds (175)
Natasha Fourouclas (831)
Lynn Kiro (981)