The singer admitted that she looks up the lyrics to Minaj's tracks online and raps to them in the car.
She told The Guardian: "I do like to rap sometimes, but that's not on the album.
"When I'm in the car and there's a song on I'll go onto Google and look up the lyrics and rap along. I do a lot of Nicki Minaj songs."
Asked her favourite Minaj lyric, she replied: "'I fly like a star in the sky, I can no longer tell I'm alive.' Basically."
Lewis previously quipped that she would rap on her new album Glassheart, adding: "I could probably go up against Nicki Minaj now. I'm actually that good."
The star recently released previews of songs on her new LP, which is released on October 15.
Watch the music video for her new single 'Trouble', which is available to download from October 7, below: