Once the jewel in the crown of Arsene Wenger's squad, Spainish midfielder, Fabregas left the North London side to join boyhood club Barcelona in 2011. But he was never quite so central a figure with the star-studded Catalan giants and Arsenal had the option to buy back their former captain in pre-season.
However, with Arsenal's squad now featuring a clutch of midfield playmakers in Mesut Ozil, Santi Cazorla and Aaron Ramsey, to name but three, veteran French boss Wenger - who this week celebrated his 18th anniversary in charge of the Gunners - felt he could do without his one-time talisman.
Chelsea, by contrast, were happy to spend £27 million ($46 million) to bring Fabregas back to London, with Blues’ manager Jose Mourinho boasting it took him just 20 minutes to seal the deal.
So far Chelsea's investment has been rewarded with seven Fabregas 'assists', the latest in this week's 1-0 UEFA Champions League win at Sporting Lisbon, while Mourinho's men have won five and drawn one of their six Premier League matches to open up a six-point lead on the Gunners heading into this weekend's matches.
"Fabregas has made a huge impact. I know you kind of expect that from him but most of our chances come from him opening up defences," Chelsea captain John Terry told the London Evening Standard. "Not a lot of people can see the passes he does let alone make it."
Meanwhile Fabregas brushed aside all talk of a conflict of loyalties in an interview with Spanish newspaper El Pais. "I remind you that I played the Champions League final against Barcelona (with Arsenal) and I swear I would have done anything to win that game - and I have been a Barcelona fan since I was a kid," Fabregas said. "So I know that when I play against Arsenal I will know who is my team, who are my colleagues and who I defend."
Arsenal have won just six points taken from 20 matches away to teams finishing in the eventual top five during the last five Premier League campaigns. But fresh from seeing former Manchester United striker Danny Welbeck score a hat-trick in the Gunners' 4-1 Champions League rout of Galatasaray, Arsenal defender Per Mertesacker believes the club are ready to break out of their rut. "We know we can do better than the two consecutive seasons (at Chelsea) before and I think we will try new things on Sunday to get a better result than last year," he said.
Sunday also sees another man up against his old side when Tottenham Hotspur boss Mauricio Pochettino, who only arrived in pre-season, faces former club Southampton - an impressive second in the table despite also losing several players to bigger clubs.