Miami, FL, USA, 28 March 2018 | Reuters

Nick Kyrgios has exited the Miami Open with a straight-sets fourth-round loss to Alexander Zverev.

Kyrgios succumbed 6-4 6-4 in his second straight loss to Zverev, having fallen to the German in Australia’s Davis Cup defeat in Brisbane in February.

Kyrgios made a subdued start to the match, seeming to be struggling with back discomfort early as he quickly dropped five of the first six games.

But he roared to life to make Zverev serve out the opening set at his second time of asking.

A loose service game at 2-2 in the second, after he was broken from 40-15 up, left Kyrgios cursing himself – and there was no way back as the world No.5 booked a quarterfinal clash with Croatian Borna Coric.

Coric edged Denis Shapovalov 7-6(2) 4-6 6-4 in their battle of the young guns.