Marseille, France (SportsNetwork.com) - Eighth seed Lukas Rosol was a first- round upset victim Monday at the Open 13 tennis event.

Ukrainian Sergiy Stakhovsky took out the hard-serving Czech Rosol 6-3, 6-2 on the indoor surface at Palais des Sports.

Another result saw 18-year-old Croatian wild card Borna Coric dismiss Uzbekistan's Denis Istomin 6-4, 7-5.

This week's top seeds are Canadian slugger Milos Raonic and last week's Rotterdam titlist Stan Wawrinka of Switzerland.

Latvia's Ernests Gulbis beat then reigning champion Jo-Wilfried Tsonga of France in last year's Marseille finale.

The 2015 Marseille champ will collect $117,000.