No Nick Kyrgios, no problem as hosts Australia advance to ATP Cup quarter-final stage

USA almost out of contention after Russia clinch tie in Perth

Australia's Nick Kyrgios and Alex de Minaur cheers Chris Guccione and John Peers during their doubles match against Canada at the ATP Cup in Brisbane. Reuters

Hosts Australia secured their spot in the quarter-finals of ATP Cup with a clinical 3-0 win over Canada on Sunday despite Nick Kyrgios' late withdrawal due to a back problem.

Australia had blanked Germany in their opening tie and qualified for the final eight stage as Group F winners after Germany’s dramatic victory over Greece which was decided by a super tiebreaker in the doubles.

Kyrgios had to pull out from the opening singles in Brisbane because of a bad back, which gave John Millman an opportunity to beat Canada's Felix Auger-Aliassime 6-4, 6-2 at the Pat Rafter Arena.

"Certainly precaution today. He was a bit stiff yesterday afternoon but also this morning," Australia team captain Lleyton Hewitt said of Kyrgios.

Alex de Minaur rallied from a set and a break down against Denis Shapovalov to triumph in the battle of next generation stars to seal the tie for Australia.

From 4-2 down in the second set, De Minaur won six straight games, leading 2-0 in the deciding set and ultimately winning 6-7, 6-4, 6-2.

"I managed to turn things around, get back into a positive mindset, get my energy back," De Minaur said.

Australia also won the doubles to complete a sweep, avenging a quarter-final defeat to Canada at the Davis Cup in November.

Meanwhile, world No5 Daniil Medvedev defeated big-serving John Isner in straight sets.

The US Open finalist hit 24 winners and made just two unforced errors in the 6-3, 6-1 rout in one hour to ensure Russia clinched the tie against the United States ahead of the doubles.

Unbeaten Russia are top of Group D, while winless United States are all but out of contention for the knockout stages in Sydney. World No19 Isner has struggled in Perth. He lost his opening match to young Norwegian Casper Ruud in three sets.

Medvedev defeated Isner, who consistently misfired his serve, and broke the American four times.

"I was very scared of his serve, so I knew I had to just wait for my chances. I was really good on return," he said.

Medvedev even out-aced Isner, who for the last four years has been the ATP's year-end ace leader.

"If you asked me before the match, I didn't think it would be possible," he said. "I was really stable on my serve and there was only one service game where I was tight."

The German pair of Kevin Krawietz and Andreas Mies rallied for a 3-6, 6-3, 17-15 win in the doubles over Michail Pervolarakis and Stefanos Tsisipas, who had earlier defeated Alexander Zverev 6-1, 6-4 in the second singles encounter to get Greece level at 1-1.

The ATP Cup features 24 nations competing in Perth, Brisbane and Sydney over 10 days with most top players using it as a platform to prepare for the Australian Open.