After Ballas performed a foxtrot routine with partner Christina Milian on this week's performance broadcast, Hough -- who was serving as a guest judge in the absence of regular judge Len Goodman -- criticized his choreography by saying Milian needs to shine and she understands, from personal experience working with the pro, how a partner basically needs to dance in front of Ballas to be seen.
While Ballas said after the show he found her comment "hypocritical" and thought it was "a little funny" she made it all about him rather than Milian, the pro dancer was apparently much more upset at Hough than he let on. In fact, he was "furious," according to Us Weekly.
"The dancers were all talking about it," a source told the magazine. "Mark was so pissed after his routine, he was in silence, just gritting his teeth for a long time. He was so angry. Julianne is like his little sister he grew up with, and for her to make that dig at him... he felt like that was just so uncalled for."
Hough's brother Derek Hough reportedly tried to smooth things over by joking around with Ballas following the incident.
"Mark kind of laughed off the remark when Derek said something to him about it, but you could tell he was just angry and didn't want to talk about it," the source added. "He kind of brushed it off."
During Monday night's show, Julianne, Ballas and Milian all laughed about the critique together, but it was clear there was tension in the room and people were surprised by the little jab. Ballas tried to uphold a forced smile and then Milian insisted about her partner, "We shine together."
Ballas and Julianne are former childhood friends and dance partners, as the actress and Derek had both moved to London in the 1990s to train with Ballas' parents Shirley and Corky Ballas.