Federer, who helped his country to a 3-2 victory against the Netherlands in a relegation play off and helped them remain in the World Group, has 11 805 points.
Serbian Novak Djokovic is second on 10,470 points, while Andy Murray retains his third place.
ATP top 10 as of September 17 (previous ranking in parenthesis):
1. (1) Roger Federer, Switzerland, 11 805 points
2. (2) Novak Djokovic, Serbia, 10 470
3. (3) Andy Murray, Britain, 8 570
4. (4) Rafael Nadal, Spain, 7 385
5. (5) David Ferrer, Spain, 5 960
6. (6) Tomas Berdych, Czech Republic, 4 965
7. (7) Jo-Wilfried Tsonga, France, 4 520
8. (8) Juan Martin del Potro, Argentina, 3 850
9. (9) Janko Tipsarevic, Serbia, 3 285 10. (10) John Isner, United States, 2 610