Arsene Wenger admits Ashley Cole's Arsenal departure was a mistake and came as a result of a "misunderstanding over a few thousand pounds."
The left-back came through the ranks in north London, making his debut in 1999.
Cole was part of Arsenal's Invincibles and had been earmarked as a future club captain.
However he left for London rivals Chelsea in 2006 amid a tapping-up storm that saw the player and the Blues hold secret talks.
Cole's exit was a major blow for the Gunners, who not only lost a key player to a rival, but the Englishman was at the peak of his powers.
Wenger had to deal with several notable departures, especially during his final decade as boss, but was resigned to the eventual exits of the likes of Cesc Fabregas.
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Yet Cole's Chelsea move is one that the former Arsenal boss puts down as an avoidable situation after the two parties clashed over a new contract.
He told beIN Sports: "Well, I would say personally, most of the time, the players gave us seven, eight, nine years and left after.
"The younger generation like Fabregas we lost early and would not have loved to lose him.
"The player I think we, internally, it was a mistake to lose was Ashley Cole.
"Because he was playing at nine, 10 years old for the club. I knew with Fabregas that taking him away from Barcelona, at some stage he’d want to go back to Barcelona.
"But Ashley Cole came out of the club. I think it was a misunderstanding over a few thousand pounds.
"At the time, we spoke about [Roman] Abramovich when he came into the game, Ashley Cole is one of the few players who developed even more and continued to develop when he left."
Arsenal had initially wanted £25m for Cole but ended up getting just £5m plus William Gallas.
The left-back would go on to have a hugely successful career at Stamford Bridge, winning the Champions League and four FA Cups.
Cole has since said: “I was a little bit hot-headed and didn’t realise what I was doing at the time as well but I don’t regret it. When I look back now, it was something maybe that was meant to happen."
The manner of his exit left a sour taste in the mouths of Arsenal fans with the player admitting it is hard knowing his reputation was so heavily affected given he started his career in north London as a junior.
