Levi Colwill has said Mauricio Pochettino's coaching "guarantees" improvement in his game because the Chelsea manager is willing to "give me that kick up the bum" he needs.
The 20-year-old resisted interest from Brighton -- where he spent last season on loan -- to sign a new long-term deal to stay at Stamford Bridge, where he has made a fine start to the campaign.
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After forming a key part of England's successful European Under-21 Championship side this summer, Colwill started all five games under Pochettino and earned his first senior call-up to Gareth Southgate's squad for this month's games against Ukraine and Scotland.
Colwill said of Pochettino: "Just working with him in general, I know I'm going to improve. I can guarantee that. He's such a good manager and he will push me, he won't let me have any off days, that's what I need.
"Someone like me, if someone lets me go to sleep I might just have a good day or a bad day. I need someone there to give me that kick up bum and say 'keep going'. That's what he does.
"[Before signing a new contract], I just spoke to him and he gave me the confidence that if I came in and trained well then you would get the chance to play.
"I'm not a player who is going to demand that I have to play, that isn't me. I wasn't brought up like that. I just wanted to know that if I got the chance to earn my spot and keep it."