South Korea’s manager made his players wear different shirts in pre-World Cup friendlies to confuse 'Swedish spies'.

Shin Tae-yong devised the clever plan ahead of South Korea's high-pressure World Cup opening game against Sweden on Monday.

"We switched them around because we didn't want to show our opponents everything and try to confuse them," Shin Tae-yong told a press conference in Nizhny Novgorod, Russia.

"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.

Shin Tae-yong devised a clever plan to put off opponents during the World Cup

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

"I think it's perfectly natural that we all try to get as much information on each other as we can."

The hugely anticipated opening game is set to be a crucial one, as both teams prepare to face tougher matches in their group against Mexico and Germany.

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Tottenham striker Son Heung-min and captain Ki Sung-yeung were the only players who wore their usual shirts against Bolivia and Senegal earlier this month, Tae-young added.

Tae-young's unusual admission comes after he received reports of a 'Swedish spy' sniffing around South Korea's training sessions.

Sweden coach Lars Jacobsson reportedly persuaded a local couple to let him use their phone near the training base to conduct surveillance with a high-performance telescope and video camera.

"It took a long car journey up the mountains to reach the house, but it was a perfect spot to observe the Korean team's training," he said, according to Reuters.

But the coach was later forced to apologise on Sunday and claimed his scout had misunderstood.

“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.