While senior footballers are trying to make the final roster for the 2018 FIFA World Cup, South Korea's under-23 national team members have also started a tight competition to earn their spots for the upcoming Asian Games.

Twenty-five players have been called up to train at the National Football Center in Paju, Gyeonggi Province, for the Jakarta-Palembang Asian Games since Monday. The U-23 side, however, was able to train with a full squad from Wednesday as some members joined the team late due to club schedules. Even head coach Kim Hak-bum was not with his team for days after he went to watch South Korea's U-19 players at the Toulon international football tournament in France.

Kim said that 90 percent of his final roster for the Asian Games will be comprised of current players training in Paju, some players with the senior national team and those who are over age 23, better known as "wild cards."

The football competition at the Asian Games is open to players who are age 23 or under, but each team can take three players who are over the age limit. Only 20 players can be on the final roster for the Asian Games.

For South Korean male footballers, winning a gold medal at the Asian Games is important because it can give them military exemption that allows them to continue their future career without interruption.

Kim has hinted that he'll use all three wild cards for the Asian Games, meaning that only 17 spots are open to those who are under 23. But considering that the U-23 footballers who already compete with the senior team, such as Red Bull Salzburg forward Hwang Hee-chan, 22, and Hellas Verona attacker Lee Seung-woo, 20, can also join Kim's team, those who are currently training at the NFC will need extra efforts to make their case for the Asian Games roster cut.

Even a well-known prospect like Paik Seung-ho said he is not guaranteed a spot. The 21-year-old midfielder plays with Girona FC in Spain after moving from the FC Barcelona B team.

"I want to receive benefits from good Asian Games result, but before that, I first need to make the final roster," he said. "I feel some nerves because those who are older than me really play well, and I have to show good performance to earn the opportunity. I want to help this team."

Kim already hinted many times that he will take Tottenham Hotspur attacker Son Heung-min to the Asian Games. Son, 25, is also looking for military exemption to extend his impressive career in Europe.

Kim has yet to unveil other wild card candidates, making U-23 players stay awake and keep up their intensity in training.

Seo Yeong-jae, a left back who recently moved to Duisburg from Hamburg's reserve team, said he is ready to show his strengths with the U-23 team.

"I will focus and work harder so that our coaches don't think about picking wild cards for my position," the 23-year-old said. "I play smart and have a positive mentality. I spent three years with Hamburg reserves, but now I get to play in the higher division, so I'll be a better player."

South Korea's U-23 team will have three friendly matches at home before having a two-week training in Indonesia to adjust to the local environment there. The football tournament for the 2018 Asian Games will be held from Aug. 14 to Sept. 1. (Yonhap)