Rather than rejoin the Gunners this summer like Flamini did a year ago, Fabregas was not wanted by Arsene Wenger - and signed with Chelsea instead.
The former Barcelona midfielder comes up against Arsenal with Chelsea for the first time, and Flamini is ready for him.
The Frenchman expects to play a big role in attempting to stop the Spaniard.
He told Arsenal.com: "I will probably mark him and it won't be an easy game because he's a great player with unbelievable talent.
"He works for the team and he's a top guy with a great mentality. He's definitely one of the players we need to be careful of on Sunday."
Fabregas has an impressive record of six assists from six games for Chelsea in the Premier League already this season, and has certainly lived up to his star billing.
Sunday is the first real test of just how bad a decision it was for Arsenal to pass on him.