Nick Kyrgios finding his motivation for tennis again after fine runs in Indian Wells and Miami

Nick Kyrgios is relishing being in the "best" mental shape of his career through his new intensity to training and a stronger focus on court.

The 21-year-old pushed Roger Federer to the limit in a classic Miami Open semi-final and beat world No 2 Novak Djokovic twice in succession in the past month.

Having long felt ambivalent toward the sport and admitted to struggling for motivation, Kyrgios has brought a new intensity to training and a stronger focus on court.

"I think my level's always been there but I think where I'm at mentally at the moment, I'm just competing for every point and playing hard and I haven't really had that mindset before," Kyrgios told reporters in Brisbane on Tuesday.

"I'm feeling motivated and I want to get out there more. I want to compete and I want to play.

"I'm probably in the best place I've ever been in."

Australia have high hopes of reaching the Davis Cup semi-finals when they play USA in Brisbane this weekend.

Meanwhile, Djokovic has said that sitting out last week's Miami Open was rejuvenating, although it meant missing the chance to win a record seventh title in the tournament.

The Serbian missed the Masters series event with an elbow injury, and he said: "Of course I wanted to be on the court and defend my title but it just didn't happen this time.

"At the same time, it was also rather refreshing to get some rest and sit out Miami at home with my wife and son. It was quality family time which I don't get enough of and it made me very happy."

Djokovic also heaped praise on the evergreen Roger Federer after the Swiss maestro won the Miami Open following his success in Indian Wells a week earlier.

"What Federer has accomplished this year is admirable and it shows that one can play at the top level even at his age," said Djokovic. "He's had his ups and downs in the last three or four years but came back swinging and revitalised after a six-month layoff last year."

Djokovic will be eager to face Spain in the Davis Cup quarter-finals in front of a boisterous home crowd in Belgrade.

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