Barbara Palvin's rumored boyfriend Niall Horan set to undergo emergency knee surgery. One Direction's 2014 'Where We Are' tour in jeopardy?

One Direction just ended 2013 with huge success thanks to the new album Midnight Memories, finishing up a gigantic tour, and even seeing some great Box Office numbers with the release of their documentary This Is Us. 2014 is definitely going to be an amazing year for the 1D lads, especially with the upcoming world stadium tour, Where We Are. But before Louis Tomlinson, Niall Horan, Harry Styles, Liam Payne and Zayn Malik can start performing again, one of them has to undergo surgery! Irish heartthrob Niall Horan is set to undergo emergency surgery in the United States on his troublesome knee.

Fans of Horan already know this, but for those of you out of the 1D loop, Niall dislocated his knee as a child and has had surgery to repair it. Unfortunately it still bothers the young singer, so he has to head back to surgery to ensure a pain-free tour in 2014.

"Niall has battled this problem since he was a child. His knee dislocates and it is very uncomfortable,' a source explained. "He's had physio sessions for years but the pain persists so surgery is the best solution to have him fully fit and ready for the demands of a long tour."

After his surgery, Niall is set to stay at the recovery clinic for ten days to make sure everything goes as planned. Then the young heartthrob will jet off with the rest of his pals for the highly anticipate stadium tour, Where We Are.