Borna Coric: stuns Federer in Halle, also denies him No. 1 spot Croatian  Borna Coric ended Roger Federer’s 20-match winning streak on grass, beating him 7-6(6) 3-6 6-2 in the Halle Open final on Sunday.He also brought  to a halt the Swiss maestro’s reign as world number one. Federer was denied a