ROTTERDAM, NETHERLANDS - Former Wimbledon runner-up Tomas Berdych and former U.S. Open champion Juan Martin del Potro reached the quarterfinals at the $1.6 million ABN AMRO World Tennis Tournament.

The second-seeded Berdych, fresh off his title in Montpellier, France two weeks ago, was leading former Australian Open runner-up Marcos Baghdatis 3-0 in the first set on Thursday when the Cypriot retired due to a calf injury.

Berdych will encounter Italian Andreas Seppi in the quarters. Seppi handled German Philipp Kohlschreiber 6-4, 6-2 on Day 4.

The third-seeded del Potro popped nine aces in handling Slovakian qualifier Karol Beck 6-4, 7-5.

Viktor Troicki, the No. 7 seed, handled Jesse Huta Galung 7-6 (7-2), 6-3. The Serbian will face del Potro in the quarters.

Fifth-seeded Frenchman Richard Gasquet secured a berth in the quarters with a 6-3, 6-2 victory over Russian Alex Bogomolov Jr. on the indoor hardcourts at Ahoy Stadium. Gasquet's opponent on Friday will be fellow former top-10 star Nikolay Davydenko of Russia.

Another quarterfinal on Friday will pit Swiss icon Roger Federer against Finnish veteran Jarkko Nieminen.

The top-seeded former world No. 1 Federer received a walkover into the round of eight here on Wednesday night when Russian Mikhail Youzhny pulled out of their scheduled Thursday second-round match, citing a left foot injury. Youzhny was the Rotterdam champion in 2007 and runner-up in 2010.

The 16-time major champion Federer was the Rotterdam titlist the last time he played here back in 2005.

The 2012 Rotterdam winner will collect $385,000.