Derek Hough injures back, may not dance Monday night

Professional "Dancing with the Stars" dancer Derek Hough injured his back and may not perform on the Los Angeles show Monday, UsMagazine.com said. If the 28-year-old dancer is, indeed, sidelined, his partner, "Glee" star Amber Riley, will dance with substitute Henry Byalikov. "[Hough's] back is severely injured -- he had a pre-existing injury," an insider told UsMagazine.com. "He hurt his back dancing with Shawn Johnson [during Season 15 in late 2012,] and he re-injured it dancing with Amber. He is determined to push through but not sure he'll be able to."