Lewis, who has filled in for the injured Kyle Walker (32) this season, started at right-back in City's 3-1 victory at Elland Road.
"It's still like I'm just playing with them," Lewis was quoted as saying on the BBC website.
"I don't feel like a first-team player. I'm doing my best to keep up with them and put in the best performance to help them win.
"I don't know when I will feel like a first-team player, it will just slowly become natural, I don't think there will be a turning point."
He named teammate Walker as one of his right-back idols.
Walker has been on the bench since returning from the World Cup but has provided Lewis with some much-needed feedback.
"The whole time he's been at City I've watched him and the way he plays," Lewis said. "He's an asset to the team and you can see City aren't the same when he doesn't play.
"I want to become a regular first-team player like he is and an asset to the team."
