The Catalan locked himself away at the club's academy from 8.30am to 8pm plotting Saturday's Old Trafford triumph.
He wrestled over the decision of how to fill the void left by Sergio Aguero's suspension and whether to throw Claudio Bravo into a derby debut. And instead of engaging in a war of words with his old rival Mourinho in the build up to the much-anticipated clash, he deployed psychological tactics on his own players.
His decision to name match-winner Kelechi Iheanacho as his lone striker was as much a message to his team as it was part of his tactical plan.
Without leading scorer Aguero he wanted to let his players know that they were heading to the home of one of their main title rivals in search of all three points.
“I thought about many other options - but I thought in the beginning to show to my players that I came to win the game," he said.