The Gunners had the chance to re-sign the Barcelona midfielder this summer, but passed up the opportunity and the Spaniard joined Jose Mourinho’s side instead.
And Flamini, who is now in his second spell at the Emirates, feels a tinge of disappointment that Fabregas did not return to north London.
“I had an amazing time with him at Arsenal and he stayed a very close friend of mine,” the Frenchman was quoted as saying by Goal.
“I’m a bit disappointed that he’ll be playing with Chelsea rather than us, but I respect his decision.
“That’s football, and I’m very happy for him because I’m sure that if he’s moving back it’s because he wanted it.
“I’m also very happy that he’s coming back to London because he’s going to be my neighbour, so I’ll see him a lot!
“It will be very strange to play against him, and it won’t be easy – we were laughing about it when I saw him a few days ago – but I’m happy because it will give me the opportunity to see him a bit more than when he was in Barcelona.”