Men's team tennis in a World Cup-style format - haven't we only just had an event like that?

Less than six weeks after Rafael Nadal helped Spain win the inaugural Davis Cup finals in Madrid, the world's best male players will again represent their countries at a rival team competition, the ATP Cup.

Set up by the men's tour with the carrot of huge prize money and ranking points, the new event features 24 teams playing over 10 days in three Australian cities in January.

Great Britain are among the nations competing after Andy Murray, using an injury protected ranking of two, made a late decision to enter.

However, former world number one Murray pulled out of the event - and the Australian Open, which starts on 20 January - with a pelvic injury just six days before Britain's opening match.

Here is everything you need to know about the new addition to the start of the 2020 tennis calendar.

What is the ATP Cup?

The 24-nation event features six groups of four teams, who each play three round-robin ties. The ties - comprising two singles matches and one doubles - are best of three.

The six group winners, plus the best two runners-up, will progress to the quarter-finals.

Group matches are taking place on outdoor hard courts in Sydney, Brisbane and Perth. The knockout stage - the Final Eight - will be played at Sydney's Ken Rosewall Arena.

The final is on 12 January, which is eight days before the start of the opening Grand Slam event of the year - the Australian Open.

There is a prize pot of 22m Australian dollars (£11.6m) and a player can win up to 750 singles ranking points.

Nine of the world's top 10 players are in action, with only Swiss great Roger Federer absent after he withdrew to spend more time with his family.

The strongest team on paper in terms of their two highest ranked singles players are Spain, with world number one Rafael Nadal and world number nine Roberto Bautista Agut.

How is the ATP Cup different to the Davis Cup?

What many onlookers from inside and outside tennis are struggling to fathom is why another national team knockout competition is taking place so soon after the Davis Cup, which itself was a re-vamped event played over a week in a round-robin/knockout format.

But there are several differences between the two.

The ATP Cup has been created by the men's tour, rather than the International Tennis Federation (ITF), which runs the 119-year-old Davis Cup.

Qualification for the ATP Cup is based on a country's top-ranked singles player, while in the Davis Cup teams play qualifying ties to reach the week-long finals.

The offer of rankings points is a feature of the new event only - a player who plays and wins all possible singles matches can earn 750 ATP rankings points. The only events where more points are on offer are at the four Grand Slams (2000 for winner), ATP Finals (1500) and nine Masters events (1000).

The number of rankings points to be awarded will depend on the ranking of the opponent and the round of the result. Doubles ranking points are also being offered.

Like at the Davis Cup, the singles matches will be best-of-three tie-break sets. But the difference in the doubles here is that there will be no-advantage scoring and a match tie-break instead of a third set.

While the Davis Cup came at the end of a gruelling season, the ATP Cup falls at the beginning and will serve as a useful warm-up for the Australian Open.

But the creation of two separate, but very similar, events at either end of an already long season has left some players having to make tough choices.

Swiss 20-time Grand Slam champion Federer withdrew from the ATP Cup for family reasons, while Russian world number five Daniil Medvedev and German world number seven Alexander Zverev skipped the Davis Cup finals.

World number two Novak Djokovic has called for the two events to be merged, saying: "Looking long term, I don't think that the two events can coexist six weeks apart. It's just a bit too congested."

Barcelona footballer Gerard Pique, whose Kosmos investment group is behind the overhaul of the Davis Cup, maintains he is open to finding a solution with the ATP over combining the events.

"We are really open to sit down with the ATP and try to arrive to a deal, to make a unique competition, a super event of two weeks and try to find the best part in the calendar," Pique said at the Madrid event in November.

"In the next few months I think we will start talking again with the ATP. And I hope in the next few months we can announce something."

Who are Great Britain playing?

If it had not been for Andy Murray's late decision to use his protected world ranking of two, Great Britain might not have qualified for the inaugural event because their other players may not have been ranked high enough.

But then the 32-year-old Scot, who only had career-saving hip surgery last January, announced on Saturday he would not play after "a setback" with the pelvic injury he has been nursing since the Davis Cup finals in November.

That has led to James Ward being called up alongside British number one Dan Evans and Cameron Norrie as the singles players, with doubles specialists Jamie Murray and Joe Salisbury completing the five-man team.

As the nation's leading player, three-time Grand Slam champion Andy Murray was able to choose the team captain and picked his mentor Tim Henman for the job.

"He's got a lot of experience, he's a fun guy to be around and he played lots of Davis Cups," Murray said in November.

Great Britain open their Group C campaign against Bulgaria in Sydney on 3 January (06:30 GMT), with world number 42 Evans taking on former Wimbledon semi-finalist and world number 20 Grigor Dimitrov in the first match of the tie.

Their other round-robin ties are against Belgium on 5 January and Moldova two days after that.

Belgium's top-ranked player is world number 11 David Goffin, while Moldova's is world number 46 Radu Albot.

Great Britain reached the semi-finals of the Davis Cup in November, losing to eventual champions Spain.

What have Becker and Safin got to do with it?

With each country's top-ranked player allowed to select their team's captain, the ATP Cup features the return of some familiar names in charge.

Germany will be captained by six-time Grand Slam champion Boris Becker (chosen by world number seven Alexander Zverev), while Russia will be led by former world number one Marat Safin (picked by world number five Daniil Medvedev).

Other captains include 1995 French Open champion Thomas Muster (Austria) and two-time Grand Slam champion Lleyton Hewitt (Australia).

Meanwhile, Bulgaria's highest ranked player Dimitrov has picked none other than himself as captain.

Schedule

Knockout stage

Thursday, 9 January - two quarter-finals (23:00* and 06:30)

Friday, 10 January - two quarter-finals (23:00* and 06:30)

Saturday, 11 January - semi-finals (00:00 and 07:30)

Sunday, 12 January - final (07:30)