Well, the question is "CAN".. then Djokovic, Murray, Federer, Nishikori, Ferrer, Fognini, Wawrinka... basically everyone from that poll group except of Berdych who´s pretty much useless in the big matches.
And there are some other guys that could definitely trouble Nadal on their best days. I can even imagine unpredictable "hit or miss" guys like Dolgopolov, Bellucci, Klizan causing him some trouble eventually. Then there are some tricky guys like Simon, Monfils, Cuevas... all capable of troubling Nadal these days. Nadal is not unbeatable on the clay anymore.