The Englishman spent last season on loan at Aston Villa but has been given playing time by Tuchel this season.
And Barkley says it is unusual for managers to take a serious look at their fringe players, but that is exactly what happened for him before the international break in September.
Asked if there a particular turning point when he realised there could be a role for you to play at Chelsea under Tuchel this season, Barkley told the club's website: "Just before the first international break I was training really well and then we had an in-house game.
"I scored a couple of goals and created a few and when he spoke to me afterwards I felt that he was impressed. Since then I was a major part of the group.
"It was just about showing my quality and being consistent and doing my extra work, but that was the turning point, just before the days off for the first international break.
"When you train under this manager he takes notice and he rewards you, which I'd heard from the lads who worked with him last season before I came back.
"It is great because some managers aren't necessarily like that. If you train well he does reward you, but not in a sense that you get rewarded just for training well, you've got to perform when you get the chance as well."
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