Kyrgios rants on 'biased' nature of 'ruined' sport

Australian Nick Kyrgios unleashed a tirade on tennis as a "biased" and "ruined" sport during his fourth-round triumph at the ATP and WTA Miami Open.

The 20-year-old from Canberra defeated 51st-ranked Russian Andrey Kuznetsov 7-6 (7/3), 6-3 to become the first Aussie in the Miami quarter-finals since Lleyton Hewitt's 2002 semi-final run.

But a dispute flared in the first set after chair umpire Cedric Mourier called a code violation against Kyrgios for swatting a ball tossed his way by a ballperson into the stands.

On the next changeover, Kyrgios told the umpire his action wasn't intentional and said a star player such as 14-time Grand Slam champion Rafael Nadal would not have been called out for the same action.

"Anyone else, like Rafa did that, you would keep it cool," Kyrgios said.

"This game is biased as anything. You all know it as well. It's biased as shit, this game. What else has it got to hide? It's ruined. Absolutely ruined."

After the match, Kyrgios said only that he stood by the comments.

Kyrgios, the youngest player ranked in the ATP top 30 at 26th, will face Canadian 12th seed Milos Raonic on Thursday for a semi-final berth.

Off to a career-best 13-3 start that includes his first ATP title last month at Marseille, Kyrgios has a track record of making off-color remarks.

Last year he drew almost blanket condemnation throughout the tennis world for lurid remarks about Stan Wawrinka's teenage girlfriend during a match against the Swiss star in Montreal.