Switzerland's Stan Wawrinka, a Swiss professional tennis player, was seeded first, besting seven other competitors, in the 2018 Diema Xtra Sofia Open.
Stanislas Wawrinka (French: [stanislas vavika; born 28 March 1985) is a Swiss professional tennis player. Stan Wawrinka 1 Adrian Mannarino 2 Gilles Muller 3 Philipp Kohlschreiber 4 Robin Haase 5 Viktor Troicki 6 Joao Sousa 7 Evgeny Donskoy 8 SUI 
