Kevin Anderson of South Africa reached the quarterfinals of the Grand Prix Hassan II by defeating Spanish qualifier Pablo Carreno-Busta 6-3, 6-3 on Thursday.
The second-seeded Anderson will next play Grega Zemlja of Slovenia, who beat Swiss qualifier Henri Laaksonen 7-6 (5), 6-1.
Martin Klizan of Slovakia also advanced by dispatching Italian qualifier Filippo Volandri 6-4, 7-6 (5).
The third-seeded Klizan will face Robin Haase of the Netherlands, who outlasted Kenny De Schepper of France 6-2, 6-7 (2), 6-3.
Anderson won six straight games to capture the first set and lead 4-0 in the second. He lost just a point on serve in the first set.
Carreno-Busta got some attention this year by winning seven futures titles and knocking out defending champion Pablo Andujar in the first round at Casablanca.
He managed to break Anderson's serve in the fifth game of the second set but Anderson held on to convert his second match point with a forehand winner.
In the other second-round matches, Zemlja saved four set points to force a tiebreaker, and took the first set with a backhand winner. The eighth-seeded Slovenian moved into a 5-0 lead in the second and clinched the victory with a forehand winner.
Voted `newcomer of the year' in 2012, Klizan struggled with his serve in the opening set, double-faulting five times and landing only 40 percent of his first serves. But the Slovakian broke serve three times to grab the first set.
Klizan rallied from a 5-3 deficit in the next set. He then wasted two match points at 6-5 but held his nerve in the tie-breaker, winning the match with a drop shot.
The seventh-seeded Haase broke De Schepper twice in the first set. But the Frenchman fought back by winning the first four points in the tie-breaker before slamming a smash to level at one set apiece.
Haase capitalized on a double fault from De Schepper to lead 2-0 in the final set. The Dutchman then saved four break points to secure the victory.