Berdych ran over Belgium's Olivier Rochus, 6-3, 6-0, and Hajek topped Kristof Vliegen, 7-6 (9-7), 6-4, Wednesday. The victories made the doubles match, won by the Belgians, meaningless.
The decision gave the Czech Republic a 2-0 record in Blue Group round-robin play, with the Czechs needing only a victory over Germany Friday to reach the title match. Belgium (0-2) cannot advance even if the team beats Spain in its final round-robin match.
Spain improved to 1-1 by beating Germany, which is also 1-1.
David Ferrer put the Spaniards ahead with a 6-3, 7-5, win over Philipp Kohlschreiber, and Nicolas Almagro clinched the point with a 6-4, 6-4, win over Florian Mayer. Germany did take the doubles match.
The Blue Group winner meets the Red Group champion Saturday in a best-of-three final.
Chile leads the Red Group with a 2-0 record and can seal a finals berth with a win Thursday over Argentina (1-1). The United States (1-1) and Sweden (0-2) play in the other round-robin match.