South Korea's coach says he made his players wear different numbered shirts in recent friendlies to confuse opponents who he says cannot tell them apart.
Only Tottenham forward Son Heung-min and captain Ki Sung-yueng wore their usual shirts against Bolivia and Senegal earlier this month, claimed Shin Tae-yong.
"We switched them around because we didn't want to show our opponents everything and to try and confuse them," said Tae-yong.
"They might know a few of our players but it is very difficult for Westerners to distinguish between Asians and that's why we did that."
Meanwhile, Sweden's manager has apologised after claims one of his scouts spied on a closed South Korea training session.
In his pre-game press conference, Swedish coach Janne Andersson addressed accusations that one of his scouts, Lasse Jacobsson, covertly watched the Koreans prepare in Austria.
"He heard about a practice session, he didn't understand that it was a closed session, he didn't understand and he watched from a distance," said Andersson.
"It's very important we show respect to all our opponents in all circumstances. If someone could interpret it in another way we regret it.
"It's been made a mountain out of a molehill."
This will be Janne Andersson's first major tournament as manager. He will attempt to become the first Sweden boss to take his team past the last 16 since Tommy Svensson in 1994.
Monday's match between the two sides could be pivotal for their progress in a difficult group also featuring world champions Germany and Mexico.
