Who needs “Dance Moms” when you’ve got Gleb Savchenko? The “Dancing with the Stars” pro joined the first-season cast of juniors as a mentor to contestant Mackenzie Ziegler and her pro partner Sage Rosen. Ziegler is the oldest contestant of the season at age 14 and arguably the most experienced (she spent several years on the aforementioned “Dance Moms” reality show), but the clip package on Time Machine Night showed Savchenko as more of a taskmaster than usual, highlighting his strict perfectionism. Did his approach get the most out of Ziegler, or was it not his tempo? Watch her routine above.

Ziegler has training in contemporary and jazz styles. She already got to perform a contemporary routine on the show, and as luck would have it this week she got a jazz number. She went back in time to the 1980s for a dance that celebrated that decade’s kitsch,...