Now that season 19 of "Dancing With The Stars" has narrowed down its contenders to the final four, the competition is nothing but stiff.  "Duck Dynasty" sweetheart Sadie Robertson will be battling Alfonso Ribeiro, Janel Parrish and Bethany Mota for the coveted Mirror Ball Trophy. The 17-year-old and her professional dance partner Mark Ballas are on top gear in rehearsing and, at the same time, making the most of their last week as dancing partners. 

"We have a really nice piece planned for Sadie's final number, and I think people are really going to enjoy it!" Ballas wrote on his Hollywood Life blog.  "The music is going to start, and I think everyone is going to identify with it because it's so iconic."  

Robertson and Ballas have been getting high scores in the course of the season, making them one to watch.  They have also become really good friends. 

"This week's game plan is to not change anything up and just keep doing what we've been doing. If it ain't broke, don't fix it! We want to enjoy each other's time and company - it's the final week that Sadie and I will spend together in this competition, and we want to have a really good time. We're going to bust a sweat and work hard, but we won't lose sight of what's important," Ballas added. 

But just before the exciting culmination of the dance program closes in, Quack Pack — or the fanbase in full support of Robertson and Ballas — earned a new member.  During one of their rehearsals, One Direction member Liam Payne paid them a surprise visit. Yahoo reports that the 17-year-old was "shocked and gushing" upon seeing the good-looking singer. Not only that. It turns out that Payne visited her family in Louisiana back in September, but they were not able to see each other as Robertson was shooting "Dancing With The Stars" in L.A. 

During their meeting, Robertson taught her new famous fan their signature move, the "Quack Attack." Payne admires the dancing duo for their great performance this season, adding that his boy band struggles going with the rhythm. Just like Payne, fans love Robertson for being true to her Christian values in everything she does, even in dancing.