Rafa Nadal and Novak Djokovic - the top two men's players in the world - will kick off a revamped Australian tennis summer on Friday with the inaugural edition of the ATP Cup team event.

The ATP Cup will see 24 nations contesting in Perth, Brisbane and Sydney over 10 days for the first time and will give the top men's players a solid platform to prepare for the Australian Open.

To accommodate the $15 million ATP Cup, which also offers 750 ranking points, the year's first Grand Slam has been pushed back from its usual mid-month start by a week and will kick off at Melbourne Park from Jan. 20.

The participating teams for the event have been determined by the singles ranking of their best player and accordingly all top seven players in the world, barring Swiss great Roger Federer have arrived in Australia.

Federer pulled out of the event to spend more time with his family. Britain's Andy Murray and Japan's Kei Nishikori are other notable absentees due to injury.

Australian Open holder Djokovic will make his ATP Cup debut for Serbia against South Africa in Brisbane on Saturday while Nadal will lead Spain into action against Georgia in Perth on the same day.

"We spend quality time and it's fun, because the concept of ATP Cup is a team concept, team format, and so it does give us an opportunity to represent our country and be a part of the team, which is not something that we do experience throughout the year very often," Djokovic told reporters.

DAVIS CUP SIMILARITY

Rafael Nadal
Rafael Nadal Reuters

The tournament, however, comes just six weeks after the inaugural edition of the revamped Davis Cup, the International Tennis Federation's flagship event, which was similar in nature and question remains if the two can co-exist in the future.

The Davis Cup was held in November in Madrid's La Caja Magica with 18 nations playing a week-long soccer World Cup-style showpiece and Djokovic, the president of the ATP's Player Council, has led calls for a merger of the two tournaments.

The new ATP event has also had major implications for the other tennis events in Australia that have traditionally been used by players to prepare for the year's first Grand Slam.

The ATP Cup left no room in the revamped tennis calendar for the mixed-gender Hopman Cup, which is popular with players and has traditionally served as a warm-up for the Australian Open.

With Brisbane hosting matches in the ATP Cup, next week's Brisbane International will be a women's only tournament while the Sydney International - one of the oldest tennis tournaments in the world dating back to 1885 - has also gone missing.

Sydney's loss proved to be Adelaide's gain as the city will host the Adelaide International from Jan. 12, where Djokovic and women's world number one Ash Barty are the top draws.

ATP Finals champion Stefanos Tsitsipas and reigning Wimbledon champion Simona Halep will also play in Adelaide.

Sydney, which will host both the knockout stage of the ATP Cup and the group stage, also has to deal with apprehensions about smoke from the deadly conflagrations impacting play.

Great Britain team captain Tim Henman said those concerns were ultimately not the priority.

"In the context of what this country is going through with the bushfires and for us having to deal with perhaps slightly poor air quality, I think right there is the perspective," he told reporters. "I don't envisage it being a problem at all."