Barcelona defender Gerard Pique believes new Chelsea manager Jose Mourinho felt 'inferior' during his time at Real Madrid.
And the 26-year-old Spanish international has blamed Mourinho's personal complex for affecting the inner workings of the national squad.
Mourinho returned to the Premier League after his time in the Spanish capital ground to a halt following limited success and player upheavals this season.
The Portuguese manager's position was further weakened as the club's great rivals – Barcelona – once again became the team to beat in La Liga.
And according to Pique, Mourinho's inability to match the on-field success of the Spanish champions contributed to the disharmony growing among the Bernabeu ranks.
"It got to the point where I think we were quite superior to Real Madrid and we were winning lots of trophies," Pique told the Daily Star.
"Mourinho tried to take the game off the field of play and I think he acted like that because he felt inferior to Barcelona.
"Everything else creates a bad vibe and generates things which aren't good for the national team or for this sport."
The negativity had the potential to throw Spain's Confederations Cup off balance, with national team-mates becoming enemies both within, and across club boundaries.
But despite tensions boiling over at times during the season, Pique was adamant common sense had now prevailed.
"Things got to the point where they crossed the line. It made for a tense atmosphere," he added.
"There was a time when there was big tension between the Barcelona and Real Madrid players.
"That's where everyone's maturity came in to play to say, 'That's enough'.
"It wasn't Mourinho who did it. It was some of the players who realised it was getting out of hand."