A focused Nick Kyrgios conceded just seven games in powering Australia to a 2-0 lead over the Czech Republic in the first day of their Davis Cup World Group tie on Friday.

The controversial world number 15 took just 95 minutes to reel off a 6-2, 6-3, 6-2 win over the 157th-ranked Jan Satral and tighten Australia's grip on the hardcourt tie at Kooyong in Melbourne.

Rookie Jordan Thompson upset Czech number one Jiri Vesely 6-3, 6-3, 6-4 in the opening singles match in two hours and six minutes.

Thompson, 22 and ranked 65, made surprisingly light work of the 54th-ranked Vesely to sink the Czech Republic's hopes of splitting the opening day singles.

Kyrgios, who was fined US$5,500 for swearing and throwing his racquet after a stormy second round exit to Andreas Seppi at last month's Australian Open, showed no such behaviour under the watchful eye of Australia captain Lleyton Hewitt.

He maintained his focus, kept his emotions in check and sent down 21 aces.

"That's my main weapon," Kyrgios said. "I'm always trying to develop that part of my game. That's what I'm aiming to do every match."

The big-hitting Kyrgios overwhelmed the hapless Satral although the Australian needed six match points to finally put away the Czech.

Kyrgios said it wasn't as easy to win against a rookie opponent as some expected.

"I had a week in Miami (after the Australian Open) and flew back so I didn't have that long to prepare -- about five days," he told reporters.

"There were some pre-match nerves. I haven't played that many matches in 2017.

"It's never easy playing a guy you don't know that well. He had nothing to lose."

Kyrgios improved his record to 5-3 in singles rubbers against Satral, who was making his Davis Cup debut.

- 'Tough for us' -

Australia can wrap up the tie with victory in Saturday's pivotal doubles through the pairing of John Peers and Sam Groth. 

Doubles specialist Peers is fresh off a Grand Slam title win at the Australian Open, while Groth reached the quarter-finals of the men's doubles in Melbourne.

Czech captain Jaroslav Navratil said former world number eight Radek Stepanek was in doubt for the doubles with an unspecified injury.

Stepanek, 38, has a history of back problems which almost ended his career in 2014.

"It's a difficult situation for us because Australia has a very good doubles team and Radek is not playing because yesterday (Thursday) he get injured a little bit so it's tough for us," Navratil said.

Thompson was handed his debut by captain Hewitt after the 27th-ranked Bernard Tomic made himself unavailable, citing scheduling issues, while Vesely took over as the top-ranked Czech player following the unavailability of world number 10 Tomas Berdych.

The young Australian began well with a break in the opening game and had few problems with the shaky Czech left-hander making five service breaks.

"It's the biggest moment in my career, the summer has been pretty good, but playing for your country is amazing and getting us off to a 1-0 lead is even better," Thompson said.

"There were some nerves at the start, but I was just glad the balls were coming off the racquet nicely."

It is the eighth meeting in the Davis Cup for the two nations, with Australia leading 7-1.

Australia won their last meeting 3-2 at the same stage two years ago in Ostrava.

Source: AFP