Fabregas moved to Chelsea this summer for around £30million after three seasons with the Catalan giants, and starred in their opening 3-1 Premier League win against Burnley on Monday.
The Spaniard had a hand in all three goals, with the highlight his sublime, caressed through ball for Andre Schurrle to make it 2-1.
Now his manager Mourinho has taken a swipe at the Barcelona management team, hinting they misused the former Arsenal man during his time at the Nou Camp.
“Fabregas was our first choice for that position. I know clearly what the player is because we were so long in the same league," Mourinho is reported as saying in the Telegraph.
“He moved to Spain also, so for the last 10 years we have been in the same league for six or seven. I know exactly what he will bring.
“For Barça he was the fake nine, the number ten and winger but I know and he knows what is his best position, so he is giving exactly what we need. Quick thinking in midfield. He brings people in the same direction. I am really happy.”
Fabregas was deemed surplus to requirements with Barcelona, following the appointment of new manager Luis Enrique.
Mourinho’s comments are the latest in a long line of history relating to Barca, having caused controversy between himself and the club as manager of Chelsea, Inter Milan and Real Madrid in the past.