Recap of Monday night's performances
Pickler, football pro Jacoby Jones, Olympian Alexandra Raisman and 16-year-old Disney Channel star Zendaya each did three dances on Monday's episode of the ABC competition.
Zendaya was perfect in the judges' eyes, earning the maximum score for each routine.
"You've only just scratched the surface of your talent," head judge Len Goodman said.
Pickler was a close second, collecting perfect 10s for her quickstep and freestyle dances, but finishing behind Zendaya in the cha-cha relay, which saw all four finalists perform to the same song.
Pickler's freestyle brought judge Carrie Ann Inaba to tears.
"You just bared your soul on the dance floor and it was one of the most beautiful things I have ever seen," Inaba said.
Raisman finished third after wowing the judges with a freestyle routine that incorporated gymnastics and stunts on vertical bars. Jones landed in last place, falling short on his action-packed freestyle that Inaba said distracted from his dancing.
Viewers were given until 11 a.m. EDT Tuesday to cast votes on Facebook. The show's hosts, Tom Bergeron and Brooke Burke-Charvet, said ABC's online voting system was down Monday night.
Each contestant will perform one last dance during Tuesday's season finale to add points to their totals. Judges' scores combined with viewer votes will determine the new champion.