"During my pregnancy I played a lot of her music," one mother, who was attending the concert with her daughter, told Vogue. Vogue's May cover star is smashing the fashion game on the Challengers press tour, giving a run for its money. While it's unclear if the couple was playing a round of singles or doubles-or if was just there to cheer Gaga on as she practices-it's clear that Gaga brought a...