Bayern players overruled Pep Guardiola's tactics before a 4-0 defeat against Real Madrid in 2014, according to his former assistant Domenec Torrent.
The two teams met in the Champions League semi-finals six years ago, with Guardiola coming up against legendary Italian head coach Carlo Ancelotti in the dugout.
Madrid were on the verge of a first European Cup final in 12 years after winning the first leg 1-0 at Santiago Bernabeu, but Bayern were expected to provide a sterner challenge at Allianz Arena.
In the end, Guardiola's men were no match for Ancelotti's side, as Real raced into 3-0 lead at the interval thanks to a Sergio Ramos double and a Cristiano Ronaldo effort.
Ronaldo doubled his tally in the second half, and Madrid progressed to the showpiece event after a 5-0 aggregate triumph, dumping the reigning champions out of the competition in the process.
Torrent, who was sat on the bench next to Guardiola that night, has revealed that several Bayern stars ignored their manager's instructions prior to the match.
The 57-year-old says the players took it upon themselves to go to toe to toe with Madrid, and he's not sure whether there would have been a different outcome had they followed Guardiola's blueprint.
"Pep's idea would have been a more wait-and-see tactic, but essential players wanted to act more urgently, more stormily," Torrent told Kicker. "There were errors in defensive behaviour when conceding goals, but there are such errors.
"Maybe with Pep's idea of more control we still would have lost 0-4, maybe even 0-5."
Torrent went on to express his belief that Philipp Lahm was as important to Guardiola at Bayern as Xavi was to him at Barcelona, having also served as the current Manchester City boss's number two at Camp Nou.
"Lahm was another Xavi for Pep at Bayern. Lahm could have played with us in Barca's big phase thanks to his game intelligence," said Torrent.
Guardiola was criticised for his failure to win the Champions League at Bayern, but he was still able to deliver unprecedented success on the domestic stage. The 49-year-old guided the German outfit to seven major trophies in total, including three successive Bundesliga titles and two DFB Cups.