The fourth-seeded Indo-Czech pair defeated the fifth seeded combination of Pakistan's Aisam-Ul-Haq Qureshi and Dutchman Jean-Julien Rojer 6-1 6-7 (3) 6-4 in a match which lasted more than two and a half hour.
They will now be up against top-seeded American brothers Mike and Bob Bryan, who got the better of the 12th-seeded British pair of Colin Fleming and Jonathan Marray 7-6 (7), 6-4 in their quarterfinal match.
Paes and Stepanek started off well and broke their rivals twice, while holding their own serve, to clinch the opening set in just 33 minutes.
In the second set, neither of the two teams conceded a single break point. Even though Qureshi and Rojer committed three double faults but fought hard enough to equalise and keep themselves in the match.
The third set was also closely-contested but Paes-Stepanek converted an all-important break point while Qureshi and Rojer frittered away the only one they got as the Indo-Czech pair sealed the issue.