Sock raced past Adrian Mannarino 6-3, 6-4 behind 11 aces. He saved both break points he faced and ended up winning three-quarters of the points on serve. A break in each set allowed him to claim the win.
Horacio Zeballos won two-thirds of the points in the first set to head off to a 6-0, 7-6 (7-1) win over Filippo Volandri.
David Ferrer, No. 3 in the world rankings, is the top seed and defending champion for the Heineken Open.
Notable deaths of 2014 [PHOTOS]
Arizona Cardinals player formally charged