Nick Kyrgios has been involved in more on-court drama, appearing to smash at least one racquet while leaving the court for a mid-match toilet break, before exiting the Cincinnati Masters in what is set to be his last match before the US Open.

It was the presence of chair umpire Fergus Murphy that seemed to upset the Australian the most during his three-set defeat to Russian top-10 player Karen Khachanov, 6-7 (3), 7-6 (4), 6-2.

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Kyrgios, who won in Washington this month in what shaped as a promising return to form, blew up several times at Murphy, with the "shot clock" before serving appearing to be the catalyst for his anger.

After succumbing to the emerging Russian Khachanov after three tough sets, Kyrgios refused to shake Murphy's hand and vented his anger towards the official, also appearing to spit in his direction.