Coach Shin previously said he would use all three wild cards for the Olympics, and they would be given to field players. While Tottenham Hotspur forward Son Heung-min and Guangzhou R&F defender Jang Hyun-soo were already tapped as two candidates, FC Porto striker Suk Hyun-jun took the last remaining spot.

All three players will make their first Olympic appearances in Rio. Shin said Suk competed with Seongnam FC forward Hwang Ui-jo for a wild-card spot until the last minute. Suk earned the spot thanks to his performance in the senior national team's friendlies against Spain and the Czech Republic earlier this month. Against the Czechs, Suk scored a goal on goalkeeper Petr Cech in the 2-1 victory. Suk, who turns 25 on Wednesday, has four goals in 10 matches for the senior squad.

"His power and concentration got better," Shin said. "Suk can shake the opponent's defense, and I thought he can display powerful performances up front."

This is the first time Korea will take two overaged forwards to the Olympics since the wild-card system was introduced at the 1996 Atlanta Games. Four years ago in London, Korea picked goalkeeper Jung Sung-ryong, forward Park Chu-young and defender Kim Chang-soo as wild cards, and all three were instrumental in the team's bronze-medal run.

Shin said he wanted to use the two wild-card spots on defensive backs, but the plan hit a road block when FC Augsburg declined to make their defender Hong Jeong-ho available for Rio. Unlike the World Cups and other international tournaments involving players of all ages, professional clubs aren't obliged to release their players for the Olympics, and those who want to participate in the quadrennial event need permission from their clubs.

Shin explained that he had to select overaged players from the 35-man preliminary list he had to submit to the Korean Olympic Committee two months ago, and thus his options were limited.

Although there is only one experienced defender on the squad with Jang Hyun-soo, the coach said the team's defense isn't weak. "People said our defense is unstable, but we have never conceded lots of goals," he said. "If we can spend some time building up the defense systemically, I don't think there will be a big problem."

Shin added that he was thinking about putting the 34-year-old defender Kwak Tae-hwi on the team as a wild card but decided against it due to his age. "The age difference between Kwak and other players is too big, and I thought that could be a problem," he said. "When we selected the wild-card players, we also thought about whether they could mingle with younger players."

Korea will depart for Sao Paulo on July 18 to set up camp there, and will face Iraq on July 25 and then Sweden five days later in final tune-up matches. Shin said the three wild-card players will join the team separately because of their clubs' preseason schedules.

Suk will first join the squad on July 19 followed by Jang six days later. Son will start training with South Korea on July 31 after completing his club's preseason friendly matches against Juventus and Atletico Madrid in Australia. "I'm not worried about the wild-card players' form," Shin said. "I told Son that he needs to be in shape through preseason matches, and I believe he will do it."

While playing Suk up front, Shin said he is thinking of using Son on the flanks, especially as a left wing forward. For the senior national team, Son, who turns 24 on July 8, has netted 15 goals in 47 matches. "I want to maximize (Son's) fortes, although I have to talk with him about which position will best suit him," Shin said. "But first, he needs to be a part of our tactics."

Shin said he will use Jang in multiple positions depending on the opponents' tactics and his players' form. Jang, 24, mainly features as a center back, but he can also play as a side back or a defensive midfielder. He has three goals in 26 matches for the senior team.

"We will use him depending on the match situations, but we are going to make him focus on only one or two positions," the coach said. (Yonhap)