The 23-year-old singer has topped the Billboard Hot 100 chart with his single 'Someone You Loved', and Lewis is still struggling to come to terms with his own success in the US.
He explained: "I feel like America's sweetheart, at least for a moment.
"At least for a fleeting moment, I feel like I'm the sweetest heart in all of the U.S. of A. It feels good. I feel terrific.
"I feel like I'm a wrestler, and I'm just walking out (to the ring) and there's an American flag, and I'm saying 'U.S.A.! U.S.A.!' That's what I feel like, a wrestler."
Despite this, Lewis - who was born in Glasgow, Scotland - cannot understand or explain his own popularity in the US.
Speaking to the 'Billboard Pop Shop Podcast', Lewis shared: "I have no f***in' idea. But I'm happy!
"I have no clue why this piano ballad has done what it's done. I never thought ... we were writing a big song here ... I just wrote a song and thankfully people seemed to like it and maybe I'll be able to pay rent for the next few months!"
Lewis plans to toast his recent success by returning to the UK soon and partying.
He quipped: "I'm on tour for the next two and a half, three weeks. So, after that two and a half, three weeks, I'm gonna go home, and I'm gonna get so f***ed up, you have no idea."
