Such was Benneteau’s dominance he wrapped up the win in 52 minutes.
The Frenchman broke the serve of his opponent twice in either set to improve his head-to-head record against the 26-year-old to 2-1.
It was all too easy for Istomin who completed victory in 58 minutes, also with two breaks of serve in either set to advance with ease.
ATP Sydney - Men's Singles Round 1
6-Julien Benneteau (France) beat Matthew Ebden (Australia) 6-2 6-2
Lukas Rosol (Czech Republic) beat Joao Sousa (Portugal) 7-6(5) 4-6 7-6(1)
ATP Auckland - Men's Singles Round 1
Horacio Zeballos (Argentina) beat Filippo Volandri (Italy) 6-0 7-6(1)
Jack Sock (U.S.) beat Adrian Mannarino (France) 6-3 6-4
Santiago Giraldo (Colombia) beat Albert Montanes (Spain) 6-1 7-6(3)