Ashley Cole became one of the most hated figures in north London when he left Arsenal for Chelsea in 2006.
The fact that the Gunners lost the best left-back in the country was bad enough, but it was made even worse because they'd sold him to a direct London rival.
The blow was only softened by the fact that William Gallas went the other way as he swapped Stamford Bridge for the Emirates.
In the end, Cole's decision to move across London paid off, as in 2012 he won the one major trophy that had eluded him during his time at Arsenal, the Champions League.
After winning that, along with the Premier League, four FA Cups, the Europa League and the League Cup, he left England for good.
The defender had a spell at Roma and is finishing his career at LA Galaxy, far away from London, but Gunners fans have never really forgiven him for leaving.
However, his recent comments about the 2003-04 'Invincibles' team, which he was a key part of at Highbury, will go some way to building bridges with Arsenal fans.
That team went unbeaten throughout the whole season and are widely regarded as the best to ever play in England's top flight.
Recently, Pep Guardiola's Manchester City have been threatening to do what Arsenal did all those years ago.
With parallel's being drawn between the two sides, Cole was recently asked who he thought would win a game between Arsenal's 'Invincibles' and Guardiola's current City team.
And Gunners fans will love his answer.
"I think the ‘Invincibles’ would win. No bias," Cole told ESPN. "I’m not sure about the similarities. But so far they have the zero for losses, so you can compare on that front."
Despite not backing Guardiola's side in a match against his old team, the former England defender did suggest that they could become the next team to go a season unbeaten.
"They’ve clicked and connected. But it’s tough to go 38 games unbeaten. Can they do it? Who knows but it’s looking good for them so far."