The Dutch tactician told of a risky mission against his compatriot while they were both based in the Netherlands
Bayer Leverkusen coach Peter Bosz has revealed he went on a 'dangerous' spying mission against Louis van Gaal that ultimately failed because of his hiding spot.
While playing at Feyenoord in the early 90's, Bosz said he was asked by his club to go undercover at an Ajax training session while they were coached by Van Gaal.
The Dutch midfielder viewed the session secretly from his car in the parking lot, however he didn't recover any useful information because of his inability to hear his countryman speak.
"It was dangerous because Ajax and Feyenoord are like cats and dogs," Bosz told Goal and DAZN.
"Unfortunately, I couldn't hear from inside the car what Van Gaal said to his players.
"That was a pity because communication is a key for van Gaal. I did not find out that much."
Bosz admits he admires the mental strength of Atletico under Diego Simeone and is wary of the team's ability for rapid transition.
"I like [Atletico's] winning mentality," he said. "They really want to win.
"Since Simeone has arrived, the development is unbelievable.
"It's not only a team that switches from defence to offense and that defends well. It's a team that plays good offensive football too and has great attackers."