After sitting last week out on Dancing with the Stars because of a neck injury, Derek Hough is back and here to stay. "I feel good and my goal is to finish the season," he tells TVGuide.com "There are only a few weeks left and I'm going to try to finish strong." While he took a break, his BFF Mark Ballas stepped in to dance with Shawn Johnson, with whom Ballas won Season 8, and the three are back together again this week for their samba trio — which will bend, if not break, the rules. Why is Hough so intent on not playing by the book? Find out below. Plus: Is this his last season?