LOS ANGELES, Nov. 6 (UPI) -- Mark Ballas is expected to fill in for Derek Hough on America's "Dancing with the Stars" while Hough recovers from a serious neck injury, UsMagazine.com said.
Hough has been partnered with Olympian Shawn Johnson for the show's current all-star edition.
UsMagazine.com said he aggravated a pre-existing neck injury during the program's Oct. 30 broadcast and couldn't dance on Monday night's show, so Ballas subbed for him.
"Derek's injury is really serious," a show insider told UsMagazine.com.
"It's likely Mark will finish out the season for him," the source said. "Derek is so disappointed but very badly hurt. He needs surgery."