Stepanek had more trouble in the second set, but managed to beat Guccione for the third time in four career meetings.
Tommy Haas beat Christophe Rochus, 6-2, 7-5, in another second-round match.
In a first-round match, wild card John Isner, who played tennis at Georgia, beat lucky loser Ramon Delgado, 7-6 (9), 6-4. Isner recorded 22 aces in the match, including his first four points.
Guillermo Garcia-Lopez withdrew from the tournament because of appendicitis. According to a tournament spokesperson, Garcia-Lopez wasn't feeling very well the past few days and finally visited a doctor on Tuesday.
Second-seeded Juan Martin Del Potro was scheduled to make his debut in San Jose against Andrea Stoppini later in the day, followed by third-seeded James Blake against Vincent Spadea. Blake bowed out of Monday's exhibition match against Pete Sampras because of back spasms.
Blake easily advances to quarterfinals at SAP
Baghdatis advances at SA Tennis Open
Jonathan Pereira Seeking Villarreal Return In Summer
