AUSTRALIA'S Davis Cup banker Nick Kyrgios promised he will "compete for every point" in future but gave notice he will remain prone to swearing and racquet throwing.
Kyrgios continued the most consistent run of his career with a resolute, low-fuss win which grabbed Australia a 2-0 lead in their Davis Cup tie against the United States at Pat Rafter Arena.
Kyrgios's 7-5, 7-6 (7-5), 7-6 (7-5) win in the second rubber was predictable on the basis of rankings and on recent form over American No.2 John Isner.
But teammate Jordan Thompson's 6-3, 3-6, 7-6 (7-4), 6-4 win over American Jack Sock, the highest-ranked player in the tie at No.15, set the Americans back on their heels.
One win from the remaining three matches will deliver Australia, underdogs in pre-tie betting, a semi-final in September against either Belgium away or Italy in Australia.
The fiery Kyrgios, often treated as the villain at overseas tournaments since he was suspended for not trying his best in a match last October, said he appreciated the support from the home crowd of 5780.
"I'm trying to knuckle down and compete for every point and that's something I haven't always done in the past," said Kyrgios, who will start favourite to win Sunday's first reverse singles match if the tie is still live.
"I still am very emotional out there. I still challenge the umpire and still say what I think. I still throw my racquet and still swear, but I will compete for every point.
"I think I'm getting there. I'm only human. People tend to forget I'm only 21."
The US originally named Sam Querrey and Steve Johnson for Saturday's doubles match against Australians John Peers and Sam Groth, but teams can make changes in the morning under Cup rules.
Hewitt felt the day's play illustrated that if a decision is made later this year to have Davis Cup matches best-of-three sets, it would make the competition, he said, a "bit Mickey Mouse".
"I'm really proud of both boys, but there's still a bloody long way to go," he said.
Kyrgios was able to adopt a front-runner's calm after he grabbed back a first-set break of serve.
The Australian No.1 argued with umpire Pascal Maria twice over calls during changes of ends, in the first set and then at 5-6 in the second set.
But he jogged to his chair with an uncustomary wide, mid-match smile when he took the second set with a drop shot.
Kyrgios racked up 15 aces to Isner's eight in taking a two-sets-to-love lead, out-serving an opponent who hit the most aces in men's tennis last year and in four of the past seven seasons.
How Sock can recover mentally and physically to win tomorrow's fourth match of the tie against Kyrgios will fully exercise the mind of his captain Jim Courier.
Courier said his team would rally around Sock and noted that his US team had lost to Croatia last year from two matches up after the first day.
Kyrgios said the win by Thompson, ranked No.79, had taken a "load of pressure" off him and his teammate had played like someone who had played 15 live rubbers, instead of his two.
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