Vienna - John Isner relied on his strong serve to beat French qualifier Kenny De Schepper 7-6 (4), 7-6 (5) in the opening round of the Erste Bank Open on Tuesday.
The third-seeded American hit 16 aces and avoided break points, but failed to convert four chances on De Schepper's serve.
Isner missed a match point at 6-5 but closed out the win on his second chance in the tiebreaker.
The 13th-ranked Isner will next play Ernests Gulbis of Latvia.
Also, Paolo Lorenzi of Italy advanced to the second round after rallying to defeat Rajeev Ram of the United States 6-7 (4), 6-1, 6-4. Ram hit 16 aces but lost his serve four times.