"Having Derek as my partner is an answered prayer," Pickler tells PEOPLE. "Right before I left Nashville for L.A., my Grandpa Ken, who is a huge fan of the show, told me he was praying that Derek would be my partner, because that's his favorite male dancer on the show."
Picker, 26, made a splash on season 5 of American Idol, which films at a soundstage next door to Dancing with the Stars. Now she hopes that returning to the building where her career got its start and teaming with three-time DWTS champ Hough, whom she calls "a phenomenal dancer," will bring her luck in the pursuit of the coveted mirror-ball trophy.
And for good measure, she's counting on her Grandpa Ken.
"Now I think I will tell him to pray that we win!" Pickler says.
Dancing's new season kicks off March 18 on ABC.