Fabregas concedes he must improve his own contribution.
"I'm not happy with my own performance," he said of his own showing in the cup tie against Real Madrid. "I have to improve a lot.
"This is the boss's system and it's not easy to get it straight away. When I play further forward, I have more mobility and that's a role I can handle - further back I need to have more discipline and I missing the patience for that."