MIAMI (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 (9-11), 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.

Chair umpire Fergus Murphy allowed the challenge, a decision that former player Brad Gilbert called "wrong" during television coverage, and replays showed the ball was indeed out.

The point was awarded to Kyrgios, which left Zverev seething, arguing that the 12th seed should not have been allowed to challenge the call after hitting the ball.

Flustered, he lost the game, which turned out to be the only service break of the set, and Zverev gave Murphy a piece of his mind at the next change over.

"You might cost me the match," he said. "You know that. The decision is absolute crap."

Kyrgios, meanwhile, was not happy either, giving the linesman a verbal spray for missing the call in the first place, but settled down to hold serve and finally clinch victory on his sixth match point, earning a semi-final berth against Switzerland's Roger Federer.