While rehearsing for tonight's show, the dance pro revealed he's been pushing Kellie harder than ever. "Sometimes the drill sergeant comes out of me and I'm like, 'No, do it again!'" the pro dancer tells E! News' Will Marfuggi. "And she goes, 'I don't hate you, but I hate your ways right now.'"
A bit of tension between the pair is understandable, given that Kellie will be performing her first ballroom dance Monday (and, thanks to a concert in Alabama, she has less rehearsal time than usual to make it all nice and perfect 10-worthy). "We're doing the foxtrot," Derek says, "which is so different from any of the other [previous dances], so she has to kind of learn from scratch. It's been trying to cram in a lot in a very short amount of time."
To hear more from this season's frontrunners about prepping for tonight's crucial dance, as well as their stress-relieving trick known as "laughing yoga," watch our exclusive interview above!