Dutch runner Sifan Hassan took a first, giant step in her bid for an unprecedented Olympic treble when she sprinted to gold in the 5000m on Monday. In Ethiopians Tsegay, Ejgayehu Taye and Senbere Teferi, and Kenya's Obiri and Agnes Tirop, the entry list featured five of the world's 10 fastest ever over the distance. READ : Morocco's Soufiane el-Bakkali …