(Photo credit: Dan Hamilton-Imagn Images) Germany's Alexander Zverev was the only one of the top four seeds to escape the upset bug during quarterfinal action on Friday at the Terra Wortmann Open in Halle, Germany. The top-seeded Zverev held off Belgium's Raphael Collignon 7-6 (10), 7-6 (2) as both players uncorked 14 aces and lost no service games during their two-hour battle. No. 2 seed Felix Auger-