Arguably the biggest game of football this weekend takes place in the unlikely location of West Java, where South Korea take on Japan in the final of the 2018 Asian Games. Rarely has a football tournament been so much about one player and onlookers around the world have found themselves fretting almost as much as those in Seoul about the fate of the Korean captain Son Heung-min.

It all ends, one way or another, on Saturday as the biggest rivals in Asia meet at Pakansari Stadium in Cibinong. The Samurai Blue would love to win but the Taeguk Warriors have to – only gold would mean military exemption for the 20 players in the Korean squad. That is the only reason Tottenham Hotspur let Son leave the early stages of the Premier League season to play in a far-flung, regional Under-23 tournament (he is one of three overage players allowed).

Victory would mean the 26 year-old could see out his new five-year contract in north London – or be sold on for a fee that reflects his abilities – without having to return home when he is 28 for 21 months of duty to his country. For his younger compatriots, it opens doors, maintains freedom of hairstyle and maximises earning potential, far beyond two years of basic army pay.

The situation has created a motivation to win that borders on painful. Coach Kim Hak-bom wrestled with who to include in the squad – and, perhaps more pertinently, who not to include – knowing that his decision could change lives in a dramatic fashion. Nicknamed “Hakbomson” in homage to Sir Alex Ferguson, Kim copped plenty of flak for calling up his former club favourite Hwang Ui-jo in one of the precious three overage playing spots. Luckily the striker, the real star of the tournament, has silenced the critics with nine goals.

Korea have taken part in the Asian Games football tournament before – and their players have won exemption before – but apart from 2014 on home soil (when Son did not play as Bayer Leverkusen refused to release him for a tournament not recognised by Fifa), not that often. This time feels much bigger. The presence and profile of Son, whose time is running out, has made a regional story into a bona fide global one.

For Korea, failure is not an option. There was severe criticism after a surprise 2-1 loss to Malaysia in the second group game when Kim heavily rotated his team, but results improved after that. Iran were defeated 2-0 in the second round and AFC Under-23 Champions Uzbekistan – seen as Korea’s biggest threat – were overcome 4-3 after extra-time in the quarters. Son couldn’t even watch the 118th minute penalty conversion from Hwang Hee-chan. Just two days later came a sixth game in 14 days, and a 3-1 win over Vietnam to earn a spot in the final against their old rivals.

In some ways, Japan have been the complete opposite of Korea in this tournament. The Samurai Blue have somewhat flown under the radar, partly because they are using this tournament in a way that Korea can only dream of: as part of planning for the future. Japan did not call up any overage players and brought a squad made up entirely of players under 21. The idea is for this group to gain experience in readiness for the 2020 Tokyo Olympics.

As such, there are zero expectation and little pressure on Japan to win Saturday’s final. It all rests on Korean shoulders, and this may be where the game is won or lost. Son’s Premier League or Champions League experience could prove a key factor, but even he may not have experienced this level of pressure before.