The men's and women's champions at the Australian Open tennis event are set to pocket four million Australian dollars (US$3.2m) each later this month, an equity often cited as one of the great examples of gender equality in sport.

When Wimbledon agreed to offer equal prize-money a decade ago, only nine out of the 44 sports which remunerate athletes paid equally. That number is now 35.

However, the remaining nine are among the biggest and most lucrative in the world: Football, golf and cricket among them.

Serena Williams is the only female in the world's 100 highest-paid athletes. Recent studies suggested gender equality in football is worse than in politics, business and medicine.

Even in tennis, away from the Grand Slams, the gap remains considerable.

Earlier this month, Nick Kyrgios pocketed $83,650 for winning the Brisbane International. Julia Goerges, meanwhile, earned $43,000 for winning a similar-level event in Auckland.

Adding endorsements, the gulf widens. World's top-ranked female tennis player Simona Halep's off-court earnings came in at $1.5m last year, dwarfed by Roger Federer, currently men's number two, who pocketed $58m.

This month, Novak Djokovic urged male tennis players to demand more prize-money.

Last year, Djokovic said male players should earn more than their female counterparts because they have a bigger following.

FIFA, football's world governing body, awarded a total prize pool of $15m for the last Women's World Cup. For the men's equivalent, the pool was $576m.

In golf, the men's world number 143, Mackenzie Hughes, earned more in 2017 ($2.36m) than the women's number two Sung Hyun Park ($2.34m).

The 2017 earnings of top-ranked golfer Dustin Johnson's caddie surpassed all but three of the top female golfers.

"It's important to understand that the money doesn't come from how well the players hit the five-iron or how accurate their putting is," Mark Lichtenhein, chairman of the Ladies European Tour, told Al Jazeera.

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"It comes from how well the events are packaged and marketed as a product. Too many women's sports are trying to compete with men's sports on men's terms. They're chasing after the same sponsors and the same TV channels.

"Because of the male-biased demographics of those channels, they don't necessarily get the same viewing figures, creating a perception that the audience isn't there for women's sports and that it's just an add-on to the men's game."

Almost 99 percent of all sponsorship money - the amount that dictates footballers' salaries and the prize pool for tennis and golf events - is directed at men's sport. Golf executives believe the women's game has struggled to attract an even share because their tournaments are often billed as space-fillers in the broadcasting schedules between men's tournaments.

Lichtenhein believes one of the key ways to increase the amount of money available to female athletes is to reach out to different TV channels and online streaming platforms not traditionally associated with sport.

"We're seeing some progress. A lot of sponsors are beginning to realise that for a relatively low price, you can reach a pretty good demographic of women, and that targeting women is perhaps more cost-effective given that women make the majority of household purchasing decisions."

Merging tournaments

Squash, meanwhile, has made substantial breakthroughs in gender equality, offering equal prize-money for the first time at the 2017 World Championships and at five of the seven elite World Series tournaments.

"We managed it by merging the men's and women's tours," Professional Squash Association Chief Executive Alex Gough told Al Jazeera.

"This allowed us to hold both events at the same location, market them to TV and sponsors as the same package, much like the Grand Slams in tennis, and then offer the same prize-money."

The European Championships at Gleneagles this year will be the first mixed golf event, held on the same course with equal prize-money.

While golf and squash aim towards parity, the greatest disparity exists in football, where Cristiano Ronaldo's 2017 earnings ($93m) dwarfed those of the highest-paid female player Alex Morgan ($3.5m).

Norway made headlines in October 2017 for offering both national teams the same salary for playing, sponsor appearances and image rights, the male players have the potential to earn far more.

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Both teams get 25 percent of the bonus payments awarded by FIFA or UEFA for qualifying for a major tournament, the men's bonus payments are far greater.

"There's a big need for FIFA to use their huge income from the men's World Cups to invest in women's football by increasing the bonuses and prize-money for their tournaments," John Didulica, chief executive of Professional Footballers Australia, said.

"That would encourage all the national federations to invest more in the women's game due to the potential financial windfall."

In recent years, the Australian federation has started investing in women's football, providing comparable minimum contracts to female players.

However in Europe, home of the game's major club leagues, the gulf in pay is huge.

Didulica believes responsibility lies on national federations to invest more and close that gap.

"At the moment, women's football is in an investment phase," Didulica said.

A lot of sponsors are beginning to realise that for a relatively low price, you can reach a pretty good demographic of women Mark Lichtenhein, chairman of the Ladies European Tour

"We can't expect it to generate the same sponsor and TV value as the men's game without first investing money to allow it to catch up commercially and in terms of quality. There's huge potential, but we can't expect female players to be Premier League standard if they're having to work part-time shifts in a coffee shop.

"It's time we began using the game's border revenue to make women's football as good as product as it can be."

However, even with considerable investment, not everyone is convinced female athletes will ever be able to achieve pay equality in sports such as football and golf.

"I'm not sure we'll get to prize-money equality in 10 years, even with all the things we're trying," Lichtenstein said.

"At the end of the day, it comes down to how many people want to watch men's sport as opposed to women's sport, and the value created by that, and that's just a fact of life."