'I'm done': Nick Kyrgios explodes over 'bulls**t' controversy at ATP Cup

Nick Kyrgios was left furious on Saturday night as Australia went down to Spain in their ATP Cup semi-final clash in Sydney.

Alex de Minaur lost a thrilling 4-6 7-5 6-1 match to Rafael Nadal, as the Australians bounced out at the semi-final stage with Kyrgios earlier delivering his poorest match of the tournament in going down to Roberto Bautista Agut.

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A shadow of the player who had racked up a 3-0 singles record and a decisive doubles win at the teams tournament, Kyrgios struggled from the outset and never recovered.

Down 5-0 in the opener, the best the world No.29 could do was hold serve to ensure he could start up the second with ball in hand.

A tighter contest ensued early in the second but, when Kyrgios coughed up a break after an ill-advised trip to the net off a second serve, the match was as good as done.

There was some controversy however when Kyrgios thought he’d served an ace on break point, only to be informed by the umpire that it was a let.

However Kyrgios was adamant the ball was well over the net cord and destroyed his racquet upon losing the game.

“That’s f***ing bulls**t,” Kyrgios could be heard telling captain Lleyton Hewitt.

“I’m done, I’m done.”

Still, it has been a good Australian Open tune-up for Kyrgios, who had logged an impressive win against world No.6 Stefanos Tsitsipas and a heroic doubles win with de Minaur over Great Britain during the tournament.

De Minaur pushes Nadal in stunning display

The man with the best motor in tennis added some power to his package but even that wasn't quite enough to get De Minaur over the finish line against world No.1 Nadal.

Spain will play the Novak Djokovic-led Serbia in Sunday night's final after the Serbs beat Russia 3-0 in the other semi-final.

Kyrgios's 6-1 6-4 defeat had left de Minaur needing an unlikely victory to push the match to a deciding doubles clash.

But adopting a similarly aggressive game plan to Belgium's David Goffin, who downed Nadal on Friday night, de Minaur was outstanding, hitting winner after winner to put the 19-time grand slam champion on the back foot.

"Obviously I knew the task at hand, and I knew that if I wanted to hurt Rafa I was going to have to play like that," de Minaur said.

Breaking Nadal on his first service game, he held firm to take the opening set and went toe-to-toe with the Spaniard for much of the second.

After a break-point chance at 5-5 to serve for the match, things then started to unravel for de Minaur.

Nadal snatched the set with his only opportunity as part of a run of six-consecutive games to effectively seal the match.

The irrepressible world No.18 pinched a break back but it wasn't enough as Nadal avoided losses in back-to-back matches for the first time since October 2016.

Spain will play the Novak Djokovic-led Serbia in Sunday night's $22 million final after the Serbs beat Russia 3-0 in the other semi-final.

with AAP