Bayern Munich manager Carlo Ancelotti said he couldn't accept a role as manager of either Barcelona or Atletico Madrid after having managed their La Liga rival Real Madrid for two seasons.
Ancelotti, 57, led Real to "La Decima" in 2014, helping the club win their historic 10th Champions League title by beating Atleti in the final.
Now the boss of Bavarian giants Bayern, who have been drawn with Atleti in the Champions League group stage, Ancelotti said the only way he could manage again in Spain would be a return to the Santiago Bernabeu.
Speaking to Marca, Ancelotti said: "No, I will never train [Atleti or Barca]. I respect the history of the rivalry and in the same way, I couldn't train either Lazio or Inter. [Ancelotti played for Lazio's city rivals Roma and both managed and played for AC Milan].
"It's my story and respect is very important. I have a lot of respect for Atletico and Barcelona, but I can't train them because I've coached Real Madrid for two years."
Ancelotti and Bayern travel to the Vicente Calderon on Sept. 28 for the second match of their Group D Champions League campaign and the Italian know he may not get the warmest of receptions from the fans of Real's crosstown rivals.
"The reception will be normal for a rival team and a rival coach," Ancelotti added. "I'll do my job, which is the challenge of winning at the Calderon.
"Things have not gone well for me there before but I want to win with Bayern."
Bayern haven't won the Champions League since 2013, but Ancelotti believes his team have the quality and the temperament to once again be crowned Europe's best club this season.
"They have missed out because of small details in the past and we'll try to reach that turning point in the best possible way.
"It's clear that our goal is to win the Champions League.
"I expect and want to win because I have never managed a victory [at the Calderon] with Chelsea or Real.
"Bayern already know how good Atletico are because they eliminated us last season. We've not forgotten."