Kei Nishikori and Marin Čilić have already stunned the tennis world by ousting two of the sport’s greats in the U.S. Open semifinals to set up the most surprising Grand Slam final in more than a decade. Now they stand on the verge of what would be a life-changing result, in more ways than one.

Most obviously there is the opportunity to etch their place in the history of the game. Lose a Grand Slam final and the achievement can be quickly forgotten (Mariano Puerta anyone?), but win it and it will forever live on, either by joining the collection of one-slam wonders or for having garnered a result that will propel them toward more top-level success. But, while it may not be at the forefront of their minds as they step out into a packed Arthur Ashe Stadium on Monday evening for the biggest match of their lives, both Nishikori and Čilić will be well aware of the huge financial awards on offer.  

Both men are already guaranteed the biggest paycheck of their careers to date, with $1.45 million going to the runner-up and $3 million to the winner. Nishikori’s largest payout so far is the 422,100 Euros ($546,216) he picked up for winning the Barcelona Open, a second tier ATP tour event, earlier this year. Čilić’s biggest payday, meanwhile, has been the 400,000 Australian dollars ($372,460) he collected when reaching the Australian Open semifinals in 2010.

That Down Under result was seen at the time as being the breakthrough for a new star of the game for the then-21-year-old Čilić. Similar things were predicted when Nishikori reached the fourth round at the U.S. Open six years ago when he was just 18. But the road to tennis’s big time has not been smooth or as quick as many predicted for either. In many ways, both are an example of the difficulties of breaking the stranglehold held over the sport’s major prizes by three of the greatest players of all time. One of the most startling facts to come out of Nishikori’s stunning win over Novak Djokovic and a frighteningly routing victory for Čilić over Federer, was that they created the first Grand Slam final since the 2005 Australian Open not to feature at least one of Djokovic, Federer or Rafael Nadal.

The trio’s dominance of that period is shown in the list of all-time prize money leaders on the ATP Tour. Federer leads the way at $84.8 million, followed by Nadal at $70.1 million and then not far behind, Djokovic with $66.1 million. No other active player has pocketed even half the amount of Djokovic. You have to go a long way down that list to find Čilić, ranked 56 all-time, with career earnings of $9.2 million and then Nishikori, who turned professional three years later than the Croat, at $6.9 million, good enough for a ranking of 87. Victory on Sunday would push either a long way up that list. For Čilić, ranked No. 16 entering the U.S. Open, it would more than double his earnings for the year, while for Nishikori, who arrived in New York with a ranking of 11, it would come close to doing the same.

The $3 million reward is likely to be a small part of the wealth that becoming a Grand Slam champion would bring. The real money for the world’s top tennis players, a category that both are on the verge of now joining, is made off the court. The 10 highest paid tennis players, men and women, collected $61 million combined in prize money between June 2012 and June 2013, but nearly $200 million in endorsements, exhibitions and appearance fees in the same period, reports Forbes.

A win for either Čilić or Nishikori will not only likely trigger bonuses from their existing list of sponsors, but go a long way to attracting new, more lucrative ones. The potential rewards for Nishikori are even greater than for his opponent. Despite having reached just one Grand Slam quarterfinal before his remarkable run at the U.S. Open these past two weeks, Nishikori ranked inside the top 10 earning tennis players of either gender for a 12-month period ending in June 2014, according to Forbes. His high ranking had little to do with prize money. The 24-year-old took home just $2 million in on-court earnings during that time frame, but made a massive $9 million from endorsements.

His status as the most successful Japanese male tennis player of all time makes him a highly marketable asset, and means there is huge money to be made from being one of the most recognizable sportsmen, period, in what is the world’s third largest economy. As the first Asian-born man to reach a Grand Slam final, Nishikori can look at what happened to China’s Li Na when becoming the first Asian player to win a Grand Slam in 2011 and lick his lips. Li signed endorsement contracts worth at least $42 million following her breakthrough win, reported Bloomberg, and is now the world’s second highest-paid female athlete.

Fortunately, both Nishikori and Čilić will have inspirational and qualified figures in their corner to guide them to success and help them thrive in the aftermath. American Michael Chang, with Nishikori, and Goran Ivanisevic, with Čilić, have played a major part in helping their charges fulfill their potential in what has become a growing trend of former greats working with the game’s current stars. Chang took home $19.1 million in his career, while fellow one-time Grand Slam winner charismatic Croat Ivanisevic sits one place above him on the all-time list, with his $19.9 million putting him at 14. The man who lifts the trophy in the world’s biggest tennis arena on Monday will go some way toward matching their mentors’ achievements both on and off the court.

U.S. Open men’s final 2014

Start time: 5 p.m. EDT

TV channel: CBS

Betting odds: Kei Nishikori 4/5, Marin Čilić 21/20 (via