Nick Kyrgios fires Australia into semi-finals of Davis Cup

With in form Nick Kyrgios still to play on the opening day, Thompson's shock result gives Australia a good chance of reaching just their second Davis Cup semi-final since 2006.

The controversial Aussie clinced the match 7-6 (4), 6-3, 6-4 to give his nation an unassailable 3-1 lead in the tie, with Jordan Thompson still to face John Isner.

The victor of the quarterfinal will play Italy or Belgium in September.

"It's fun to have a breather and have something to play for tomorrow", Courier said.

The United States has won a record 32 titles with Australia second with 28.

But if Kyrgios can replicate his stunning straight-sets win over John Isner, Hewitt warned it would take a mighty performance to beat his 21-year-old charge.

Sock is 15th and Isner 23rd in the ATP rankings, while Kyrgios is 16th and Thompson 79th.

A whipped forehand return got the set back on serve at 4-3 but Kyrgios needed an ace to save a set point and force the tiebreak.

"In my opinion I think he's a lot more mature now", Isner said of Kyrgios.

Taking on the highly-fancied world number 15 and U.S. number one Jack Sock, the Cherrybrook tennis star in just his second Davis Cup tie won 6-3, 3-6, 7-6 (7-4), 6-4 in just over three hours. In that semifinal match, most of the crowd was in favor of Federer, the Australian Open champion who also won at Indian Wells before Miami.

Kyrgios lost a quarter-final to the big-serving Querrey five weeks ago in Acapulco, Mexico and the Americans obviously believe his game style could disrupt the Australian No.1.

"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.

"They are likely to pick red clay at Roland Garros or Monte Carlo for the clash and I will do my best to make myself available for the semis because we all value playing for our country", Djokovic said.

He broke Querrey twice after the American led 4-1 as he attempted a comeback in the third set.

Sock served out the third set 6-2 with growing confidence and both Americans left the court for a break.

Pouille, the world number 17 and his team's top singles player in the absence of Jo-Wilfried Tsonga and Gael Monfils, swept the breaker before dominating the decider.