Top-seeded Fabio Fognini retired with a right foot injury while trailing Michal Przysiezny of Poland 6-3, 5-3 Thursday in the second round of the St. Petersburg Open.
The 17th-ranked Italian, who was looking for his third title, struggled with his right foot throughout the match and never threatened his opponent with a break.
Also, fourth-seeded Dmitry Tursunov advanced to the quarterfinals by beating Russian qualifier Konstantin Kravchuk 6-3, 6-0. Tursunov will next face Joao Sousa of Portugal, who rallied to beat Sergiy Stakhovsky of Ukraine 3-6, 6-4, 6-0.
Seventh-seeded Lukas Rosol defeated Russian wild card Karen Khachanov 6-4, 6-4.