Belgrade - Second-seeded Andreas Seppi of Italy and Joao Souza from Brazil advanced to the Serbia Open quarter-finals on Wednesday.
Seppi defeated Ivan Dodig of Croatia 6-4, 6-4, while Souza won after Serbian wildcard Dusan Lajovic retired because of an ankle injury.
Later, fourth-seeded David Nalbandian and eighth-seeded Gilles Muller of Luxembourg are in action.
Results on Wednesday from the Serbia Open on clay at Tennis Centre Novak (seedings in parentheses):
Andreas Seppi (2), Italy, def. Ivan Dodig, Croatia, 6-4, 6-2.
Joao Souza, Brasil, def. Dusan Lajovic, Serbia, 4-2, retired.
Gilles Muller (8), Luxembourg, def. Eduardo Schwank, Argentina, 6-3, 7-6 (7/0).
David Nalbandian (4), Argentina, def. Aljaz Bedene, Slovenia, 6-4, 6-3.