Last week's Rotterdam runner-up Juan round winner Thursday at the Open 13 tennis event.

The fourth-seeded former U.S. Open champion del Potro was tied with Nikolay Davydenko, 6-7 (6-8), 6-4, when the former world No. 3 Russian retired after two sets. The 6-foot-6 del Potro smacked 16 aces before moving on.

The French faithful were treated to a pair of wins on Day 4, as fifth-seeded Richard Gasquet popped 10 aces in whipping Russian Igor Kunitsyn 6-3, 6-2 in 72 minutes and Michael Llodra fired up 19 aces in taking out sixth-seeded Ukrainian Alexandr Dolgopolov 6-4, 5-7, 7-6 (7-5) on the indoor hardcourts at Palais des Sports. Gasquet will battle the formidable del Potro on Friday.

Llodra titled here in 2010 and was the Marseille runner-up in 2009.

Another Friday quarterfinal will pit top-seeded Jo-Wilfried Tsonga against fellow Frenchman Edouard Roger-Vasselin. Tsonga captured the Marseille title in 2009.

The newest Marseille champ will collect $120,000.