Bolstered by a 90 percent first-serve percentage (61-of-68), Berdych, 26, defeated 26-year-old Simone Bolelli 6-3, 4-6, 7-5, 6-2 on the indoor hardcourt at CEZ Arena.
Prior to Berdych taking the court, Stepanek faced top Italian Andreas Seppi. Seppi fought hard but could not outlast Stepanek, a former world No. 8, who won 4-6, 6-4, 6-3, 3-6, 6-3 in a grueling three hour, 50 minute match.
The best-of-five tie continues Saturday with a doubles match between the Czech team of Frantisek Cermak and Lukas Rosol against Italians Daniele Bracciali and Potito Starace. If the Czechs fail to close out the tie on Saturday, Berdych will face Seppi on Sunday followed by Stepanek versus Bolelli if necessary.
The Czechs, who are 7-3 all-time against Italy, and the Italians each own one Davis Cup championship.
The winner in Ostrava will face the Serbia-Sweden victor in the quarterfinals in April.