Updated

Nice, France (SportsNetwork.com) - Top-seeded Frenchman Gilles Simon pulled out of the draw, while third-seeded defending champion Ernests Gulbis was a hard-fought second-round winner Wednesday at the Nice Open, a final clay-court French Open tune-up.

An injured Simon was scheduled to meet Aussie James Duckworth, but decided to withdraw. Duckworth then beat French lucky-loser Quentin Halys, making his ATP debut, 7-6 (7-0), 7-6 (7-5).

The Latvian Gulbis, meanwhile, held off Ukrainian Alexandr Dolgopolov 7-5, 4-6, 6-1 on the red clay at Nice Lawn Tennis Club. It marked Gulbis' second match win of the year.

Gulbis beat Argentine Federico Delbonis in last year's Nice finale.

In other action involving seeds, No. 4 Leonardo Mayer of Argentina leveled French wild card Lucas Pouille 6-4, 6-0 and Austrian Dominic Thiem was leading No. 6 Nick Kyrgios 4-3 in the opening set when the Aussie retired.

Also on Day 4, rising Croat Borna Coric got past Italian qualifier Gianni Mina 7-6 (7-4), 6-3 and Serb Dusan Lajovic topped Spaniard Pablo Carreno Busta 6-3, 4-6, 7-5.

Thursday's quarterfinals will pit second-seeded American John Isner against Lajovic; Gulbis versus Thiem; Mayer against eighth-seeded fellow Argentine Juan Monaco; and Duckworth versus Coric.