Melbourne VIC, Australia, 3 March 2016 | AAP

Sam Groth is ready to get in the face of big-serving American John Isner after replacing Nick Kyrgios as one of Australia’s Davis Cup singles hopes.

Groth was named for singles duties in the World Group first-round tie at Kooyong starting on Friday after Kyrgios was ruled out with a severe virus.

World No.77 Groth is also slated to play doubles with John Peers, although team captain Lleyton Hewitt, who came out of retirement to replace Kyrgios in Australia’s four-man line-up, may yet step in.

Groth’s 2016 results – one win against six losses – suggest otherwise but he said he was hitting the ball as well as ever on the temporary grass court.

He said he went to Hewitt through the week and said he was ready to play singles if required.

“I’m a different player when I come into this (Davis Cup) environment and on grass as it’s my favourite surface and where I’ve had my best results,” Groth said.

“I lost a few tight matches over the last few weeks but … I’m ready. I actually feel like I’m hitting the ball as well as I can possibly hit it.”

The 28-year-old has never played American No.1 Isner before but the pair boast some of the biggest serves in the game.

Isner stands 208cm tall, or 6’10” on the old scale.

Groth said he didn’t expect many long rallies and hoped to trouble the world No.11 by rushing the net when he got the opportunity.

“I’m going to break his rhythm up; I’m going to come forward and definitely make him feel uncomfortable,” Groth said.

While he has avoided taking on world No.27 Kyrgios, Isner said the match-up against Groth on grass wouldn’t be easy.

“For one, he definitely enjoys playing Davis Cup,” Isner said.

“I think he might prefer a grass court over any other surface and, of course, he serves huge, just as I do, but he gets to the net.

“It is a different type of game to most players today, so it is a different kind of challenge, for sure.”

Find more information about the tie on our dedicated Australia v United States Davis Cup page.