BitFenix Spectre 120mm Case Fan and Asus z87pro pin issue

Hi Team, I was recommended to buy some BitFenix Spectre 120mm Case Fans for my Asus z87pro board. The trouble is that the fans only have 3 pins and the mobo has multiple fan inputs setup to accept four pins. My specific questions are: will i damage my mobo if I try to use these fans, and secondly, which of the four pins should i insert the three pins into? Thanks for looking