South Korea has revealed that it swapped shirts of players to confuse the opponents during pre-world cup friendly matches.

South Korea's football coach Shin Tae-yong claimed that only Tottenham forward Son Heung-min and captain Ki Sung-yueng wore their usual shirts against Bolivia and Senegal earlier this month, reported BBC.

"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. All coaches probably feel their opponents are always spying on them.”

Meanwhile, Sweden team manager has rendered an apology after claims of his scouts spying on a closed South Korea training session surfaced.

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"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," Swedish coach Janne Andersson in a press conference said addressing the accusations of his aide watching the session in Austria.

"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."

The group has become trickier after the defending champions suffered a shock loss against El Tri on Sunday.