CASABLANCA, Morocco (AP) -- Second-seeded Martin Klizan of Slovakia withstood a strong challenge from Germany's Dustin Brown to win 6-4, 4-6, 7-6 (5) and reach the quarterfinals of the Grand Prix Hassan II on Wednesday.
In an evenly-matched contest, both players had three aces and dropped serve four times each.
Klizan's quarterfinal opponent will be the winner of a later match between Spain's Nicolas Almagro and Argentina's Carlos Berlocq.
Sixth-seeded Andreas Haider-Maurer of Austria also advanced to the last eight after beating Spaniard Pablo Andujar 7-5, 6-3.
Haider-Maurer, who had nine aces and saved all four break-point chances on his serve, next plays either fourth-seeded Marcel Granollers of Spain or Bosnian Damir Dzumhur.
They were also playing later Wednesday at the clay-court tournament.