'This is a defining moment in where he can go'

Nick Kyrgios's stunning performance in Australia's Davis Cup victory over USA has seen him receive a raft of praise.

Kyrgios sent Australia through to the Davis Cup semis with an emphatic straight-sets win over Sam Querrey on Sunday to go with his win over John Isner on Friday.

Kyrgios prevailed 7-6 (7-4) 6-3 6-4 in Sunday's first reverses singles match, giving Australia an unbeatable 3-1 lead.

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And according to Aussie tennis greats Todd Woodbridge and John Fitzgerald, the weekend will go down as a turning point in the youngster's much-maligned career.

Kyrgios. Image: Getty

"This is a step forward in his career," Woodbridge said in commentary.

"This weekend is a defining moment in where we can see him go."

Fitzgerald credited Davis Cup captain Lleyton Hewitt with Kyrgios's new-found maturity.

"I think he's learning, he's maturing," Fitzy said.

Hewitt congratulates Kyrgios. Image: Getty

"He's got a great stable influence in Lleyton and in difficult situations full of pressure you need that.

"He's played a mature type of game this weekend and he really committed himself to the cause."

American captain Jim Courier says Kyrgios can become one of the world's top five players by the end of the year if he continues at his current trajectory.

Currently ranked No.16 in the world, Kyrgios has been one of the ATP Tour's form players over the last two months, beating Novak Djokovic twice and battling Roger Federer in a classic Miami Open semi-final, which has been described as one of the best non-grand slam matches ever seen.

"It's all in his hands," Courier said.

"You see when he's engaged and focused and concentrating and resilient - down a break in three different sets and found a way to win - that's a player who can and should be top five in the world by the end of the year, if he carries that through and if he's lucky with good health.

"It'll be exciting to watch - it always is with him, one way or another.

"When you see players that have so much skill and charisma start to put it together, it's exciting for everyone involved in tennis.

"Maybe not the guys in the locker room who have to play against him, but for everyone else involved in the sport, it's a great thing if Nick can find his potential.

"He's getting close to it."

Kyrgios says it was a relief to have won despite the added expectation generated by his performances since his shocking second-round loss at the Australian Open, which has proved a turning point in his career.

"I've always had a fair bit of expectation on me, ever since that quarter-final at Wimbledon run when I was 19," he said.

"I kind of haven't gone onto a court without a bit of expectation, so I'm used to it.

"But at the same time, it feels good. It never gets easier."

with AAP