The Davis Cup can become the one definitive team event in tennis, says the president of the International Tennis Federation.

David Haggerty has brokered a new deal to reform the tournament, which he says will provide an extra $25m a year for tennis development around the world.

However, the ATP is planning to hold a revamped World Team Cup in Australia in the first week of January from 2020, five weeks after the first staging of the new week-long 18-team Davis Cup finals.

Haggerty says negotiations are ongoing with the ATP "to run one team event - the best that we can".

"We think Davis Cup with its 118-year history has a great reason to be that event, and I think by working together with the ATP, and tennis ...why not?" Haggerty told BBC Sport.

A $3bn, 25-year partnership has been agreed with Kosmos, the investment group founded by the Barcelona defender Gerard Pique.

Kosmos will be pouring around $125m into the sport each year, and Haggerty said "the economics are there for them to be able to make some money as well".

He also confirmed Madrid will host the Davis Cup finals in 2019 and 2020, before the competition moves elsewhere. In 2019, it will take place at the Caja Magica, which stages the Madrid Open in May.

And despite the ATP's plans for their own World Cup event, Haggerty hopes that, after discussions, the Davis Cup will be able to claim its place as the key team event in the sport.

How much richer might tennis be?

The ITF has licensed the rights to the week-long Davis Cup finals to Kosmos for 25 years from 2019.

In return, Kosmos has promised to invest about $125m into the sport each year. Haggerty says a deposit of $18m has already been paid into the ITF's bank account with the rest of the first year's money to follow in January.

Of the $80m earmarked for the Davis Cup, $20m will go into prize money, and $16m into marketing and staging costs.

The remaining $44m will be the ITF's licence fee, which Haggerty says will lead to a $25m increase in the amount of money it will be able to distribute to member nations and development projects each year.

The remaining $45m will be for the other events the ITF and Kosmos wish to stage in due course, such as a winner-takes-all competition and a mixed team event similar in format to January's Hopman Cup.

Will Kosmos be able to foot the bill?

The money pledged by Kosmos is eye-watering, by tennis standards.

"We used Deloitte as an outside third party to look at the numbers and the business plan, so we had the comfort as we were making the decision," Haggerty says.

"It is a significant and vast amount of money which we are excited about, but we know the economics are there for them to be able to make some money as well."

The hope is that broadcast rights and sponsorship for the finals will be far more lucrative now the venue and the teams are known in advance.

Will the very best players play?

This is the $3bn question, and crucial to the success of the new venture.

Switzerland and Serbia will have to win a preliminary round in February to qualify for the finals, but even if they do, will Roger Federer and Novak Djokovic commit to play?

Federer has already warned that the Davis Cup "should not become the Pique Cup", and there may be a clash in years to come between the Davis Cup and the Laver Cup, which is partially owned by Federer's management company.

The Laver Cup has thus far taken place two weeks after the US Open, which is a slot the ITF and Kosmos are eyeing for the Davis Cup from 2020.

Pique told Le Figaro in August that he wants the competition to be staged in September, as it is a much better time for the players.

Will tennis have two competing world team cups?

Next year's event will definitely be held in November, which means the ATP's proposed World Cup would follow on just five weeks later.

That is a scenario the ATP chief executive Chris Kermode has described as "insane," and yet the ATP and Tennis Australia have signed a deal to stage a January World Cup from 2020. The contract is understood not to have an exit clause.

Regular discussions have been taking place between the ATP and the ITF in recent weeks to see whether some sort of compromise can be struck.

"My business history has always been trying to work together and collaborate," Haggerty says.

"I'm excited that we're having the conversations again. I don't know what the outcome will be, but I think it's better for tennis if tennis can work together. We should be able to work together."

For the moment, Haggerty is ruling out unilateral action, preferring instead to build a consensus through conversation.

"Almost every week in the calendar has something, so if we were to try and move into any different week we would be taking someone on and that's why I think sitting together with tennis is the best solution."

Money is not the only sticking point, but sources suggest ITF/Kosmos' initial $5m a year offer to the ATP for a co-sanctioned event was considered inadequate, especially as they were hoping to secure 1000 ATP ranking points for each of the winning team in return.

Will the Fed Cup get the Kosmos makeover?

Reform of the Fed Cup, meanwhile, is still lagging behind but Haggerty rejects Martina Navratilova's belief that the women's team competition has become an "after-thought."

The Fed Cup will retain its current format in 2019, but the hope is that from 2020, it will either work in the same way as the reformed Davis Cup, or culminate in a four-team end-of-year final.

"From here we'll be focusing more on Fed Cup," Haggerty explains.

"I don't think the Fed Cup has been an after-thought. I think it came down to how much we could take on at one point in time.

"Fed Cup is very, very important. Tennis is a great gender equality sport - we want to do the best we can for the Fed Cup competition. We're taking a little bit more time, so it will be a year later, but it will be a great result."