Andy Murray is set for an “extended spell” on the sidelines after he suffered a serious ankle injury during his defeat to Tomas Machac at the Miami Open.Murray lost a marathon encounter to the Czech player by a 5-7 7-5 7-6 (5) score, but has seemingly left America with a more significant issue.During the 10th game of the final set, Murray collapsed to the floor after he hurt his ankle when racing towards the net, having sealed the point which won the game.A medical time-out was initially called for the three-time major winner, but he picked himself up and continued, only to lose the decider on a tie-breaker.The 36-year-old, who is set to retire later this year, has now confirmed the severity of his injury with both his Anterior Talo-Fubular ligament (ATFL) and Calcaneofibular ligament (CFL) ruptured.