CASABLANCA, Morocco -- 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 Spain's Nicolas Almagro, who did not concede a single break-point chance in a 7-5, 7-5 win against 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 Bosnian Damir Dzumhur, who was leading 3-0 against Marcel Granollers, when the fourth-seeded Spaniard retired.
Top-seeded Guillermo Garcia-Lopez is in second-round action Thursday when he takes on Russian Mikhail Youzhny.