William Gallas says he enjoyed working under Jose Mourinho more than he did Arsene Wenger, with the Portuguese more demanding of his players.
He first linked up with the Blues in 2001, allowing him to form part of a successful era under Mourinho – following his arrival in 2004.
Gallas would win two Premier League titles under the Portuguese before crossing London to link up with Arsenal as part of the deal which took Ashley Cole in the opposite direction.
Four seasons at the Emirates delivered no tangible reward, with the Gunners in the midst of a nine-year trophy drought at that time.
Gallas, though, considers both Mourinho and Wenger to be born winners, with the former taking a more hands-on approach in pursuit of success and the latter prepared to offer his squad greater freedom.
He told Soccer AM: "Both managers want to win trophies but with Jose he will show you every day at training [what needs to be done].
"If you are not 100 per cent he will stop the training and say to you 'what's wrong with you? Why don't you train? If you don't want to train just go outside and run, because what I want and what I expect from you is to give me everything'.
"And with Arsene it's a little bit different.
"You have to be more responsible to manage yourself so he won't be behind you all the time and that makes a difference.
"So for me it was very good to be with one manager who was always behind me."
Mourinho’s methods have seen him lift the Community Shield and EFL Cup with Manchester United this season, while progressing positively in the FA Cup, Europa League and the Premier League top-four tussle.
Wenger, meanwhile, is facing further questions regarding his future at Arsenal, with his philosophies drawing criticism on the back of a disappointing run domestically and in the Champions League.