Argentina's Juan Martin del Potro and Czech Tomas Berdych, the first and third seeds at the ABN Amro World Tennis Tournament in Rotterdam, advanced to the quarterfinals with victories Thursday over Frenchmen Paul-Henri Mathieu and Nicolas Mahut, respectively.

Del Potro the defending champion and world No. 4, breezed through the early part of the match at this Dutch indoor hard-court event, but he faced much stronger resistance from his opponent in the second set.

The 25-year-old was unable to break the Frenchman's serve in that set but his own strong serving (10 aces and 87 percent winning percentage on first-serve points) and powerful ball striking off the forehand side were enough to send him through to the tournament's final eight with a 6-2, 7-6 (7-2) victory.

He will next take on big-serving Latvian Ernests Gulbis, who upset Bulgarian Grigor Dimitrov 6-4, 7-6 (7-3), in Friday's quarterfinals.

Berdych, meanwhile, saved all four break points he faced in cruising to a routine 6-4, 6-3 win over Mahut.

Next up for the world No. 7 will be big-serving Pole Jerzy Janowicz, who blasted 18 aces in a 6-4, 6-4 victory Thursday over German Tommy Haas.

Second-seeded Andy Murray of Scotland also advanced to the quarterfinals with a 6-4, 3-6, 6-3 win Thursday over Austrian Dominic Thiem and will next play Croatia's Marin Cilic. EFE