Updated

Nice, France (SportsNetwork.com) - Top seeds John Isner of the United States and Latvia's Ernests Gulbis were among Wednesday's second-round winners at the Nice Open, a final clay court French Open tune-up.

Isner popped eight aces in easing past qualifier, fellow American and good friend Jack Sock, 6-4, 6-3, in 77 minutes, while the Gulbis fought back to best Slovak and recent Munich titlist Martin Klizan, 6-7 (4-7), 6-4, 6-1.

Next up for Isner will be Argentine Federico Delbonis, while Gulbis' quarterfinal opponent will be fifth-seeded Russian Dmitry Tursunov.

The seventh-seeded Delbonis handled French wild card Paul-Henri Mathieu, 6-2, 6-4, and Tursunov dismissed Dutchman Robin Haase, 6-3, 6-4.

Also Wednesday, fourth-seeded Frenchman Gilles Simon gutted out a three-set win over Austria's Dominic Thiem, 6-3, 4-6, 6-2. Simon will next meet Argentine Carlos Berlocq, who upset sixth-seeded Frenchman Nicolas Mahut, 6-2, 6-3.

Argentine qualifier Leonardo Mayer drove out eighth-seeded Frenchman Edouard Roger-Vasselin, 6-4, 3-6, 7-5, and will next face reigning Nice champion Albert Montanes. The Spaniard rallied for a 4-6, 6-3, 6-2 win over American lucky loser Sam Querrey, who replaced an injured Frenchman Gael Monfils in the draw.

Monfils was the third seed and had a bye into the second round. His scheduled meeting with Montanes would have been a rematch of last year's Nice final, which was won by the Spaniard.