Hanescu, a semi-finalist in Casablanca last month, broke his opponent five times and saved all six break points he faced. The Romanian will next meet fourth-seeded Andy Roddick of the United States.
Pere Riba also advanced by beating Guillaume Ruffin of France 6-2, 6-2. The Spaniard, who dropped only five points on first serve, next plays fifth-seeded Alexandr Dogolpolov of the Ukraine.
Results from the Nice Open ATP tournament on Monday (x denotes seeding):
First Round
Victor Hanescu, Romania, def. Benoit Paire, France, 6-0, 6-1.
Pere Riba, Spain, def. Guillaume Rufin, France, 6-2, 6-2.
Pablo Andujar, Spain, def. Grigor Dimitrov, Bulgaria, 5-0, retired.
Denis Istomin, Uzbekistan, def. Olivier Rochus, Belgium, 6-2, 7-6 (5).
Andreas Seppi, Italy, def. Edouard Roger-Vasselin, France, 3-6, 6-3, 6-2.