Both seeded players in action lost Monday during the opening round of the ATP Tour's Sofia (Bulgaria) Open.
Italy's Gianluca Mager upset sixth-seeded Adrian Mannarino of France 6-3, 6-2, and France's Benoit Paire knocked off seventh-seeded Alejandro Davidovich Fokina of Spain 6-4, 7-5.
Mager had lost his first-round match in three of his past four tournaments, including the U.S. Open. He saved the only break point he faced against Mannarino. Paire, who ended a three-match losing streak that featured an opening-round defeat in New York, finished with an 11-1 advantage in aces against Davidovich Fokina.
In the event's only other match Monday, Serbia's Miomir Kecmanovic topped Bulgarian wild-card entrant Adrian Andreev 7-6 (7), 6-4.
San Diego Open
San Diego native Brandon Nakashima broke serve on the final point of the match to complete a 6-7 (5), 6-1, 7-5 win over Italy's Fabio Fognini in the first round of his hometown event.
Nakashima, 20, finished with eight aces and just two double faults. Fognini double-faulted nine times and had only one ace.
Elsewhere in the opening round, Russia's Aslan Karatsev topped Argentina's Federico Delbonis 6-1, 7-5. A San Diego high school product, 23-year-old Taylor Fritz, played the late match against Italy's Salvatore Caruso.
--Field Level Media