Australia's Davis Cup captain Lleyton Hewitt is backing young guns Nick Kyrgios and Bernard Tomic in the upcoming tie against the United States but stressed it will be tough.

Tomic and Kyrgios were Tuesday announced as part of the Australian team which also includes Sam Groth and doubles specialist John Peers to play the World Group first round tie on March 4-6.

"I believe in both of them," Hewitt said of world number 21 Tomic and Kyrgios, who won his first ATP title at the Marseille Open on Sunday.

"I think the match-ups can work in our favour. But it's going to be tough tennis, you know and pressure and expectation always plays a massive part in Davis Cup," the former world number one said.

"But Bernie, in particular, has got a really good Davis Cup record and it's taken absolute quality players and quality tennis to beat him in Davis Cup."

USA captain Jim Courier has announced John Isner, Jack Sock and twins Bob and Mike Bryan on his roster for the event at Kooyong, Tennis Australia said Wednesday.

Kyrgios and Tomic both have undoubted talent but also chequered reputations after a number of brushes with the authorities.

In his first Davis Cup contest as captain, Hewitt has also given Peers his first chance to play in the competition after "a tremendous couple of years".

"Obviously the doubles is always a crucial match, but I feel at the moment we're going to be slight underdogs no matter who we put in, purely [because] we're expecting the Bryans are gonna be on the other side of the net," he said.

Kooyong, the former home of the Australian Open, is hosting its first Davis Cup tie in a decade with a purpose-built grass surface installed on centre court.

The Australia tie against the USA will be the 46th meeting of the two nations, with the USA leading Australia with 25 wins to 20.

The winner of the March tie will play move into the quarter-finals against either Croatia or Belgium.