(Reuters) – Tempers flared between Nick Kyrgios and Alexander Zverev late in their Miami Open quarter-final on Thursday when a botched line call and contentious decision by the chair umpire to allow a challenge on the point caused both players to react angrily. The pivotal moment of the Australian’s 6-4 6-7(9) 6-3 triumph came on the first point of the sixth game in the deciding set, when a lob from Germany’s Zverev sailed long. The linesman mistakenly called the ball in and Kyrgios, despite believing it was out, decided to try a low percentage ‘tweener’ shot between his legs before challenging.