Simon Cowell Details His First Encounter with Kelly Clarkson on American Idol : 'Stay Away from Me'

Simon Cowell is reflecting on the start of American Idol — and the role Kelly Clarkson played in making the reality singing competition into the success it is today.

On Tuesday, the "Since U Been Gone" singer was honored with a star on the Hollywood Walk of Fame. During the ceremony, former Idol judge Cowell delivered a speech in her honor.

"I actually thought I was being punked on the first day. Paula [Abdul] resigned, every singer was out of tune, and I thought, 'Well this is a joke.' It got worse, progressively," Cowell, 61, said. "So I thought this is an absolute disaster. Like, why did I come here?"

He continued to Clarkson, 40, "And thank God, I remember the day we met you. I remember not just your voice, but your personality. I'm gonna be honest here, I didn't realize at that point, honestly how good you were. I just liked you. And I was so thankful."

Michael Buckner/Variety via Getty Randy Jackson, Simon Cowell, Kelly Clarkson

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Cowell then recalled the first time he approached her — and revealed the hilarious response Clarkson gave him.

"I went up to you afterwards because, obviously, I was thinking, 'I think you're gonna win this show.' I said, 'I just want to say, that was amazing, Kelly, and I am here.' You turned around to me and said, 'Simon... Without being rude, I would much rather we do not talk — seriously until the end of the series.' And I'm like, 'Wow, what does that mean? It means stay away from me. I know what I'm doing. I'm focused.'"

The "Breakaway" singer then interjected and jumped to her defense: "I didn't wanna talk to anyone involved that was voting us through. I was just trying to be respectful. Also, I didn't want you getting in my head — you mess with all those people."

Cowell responded, "It's taken her 20 years to get that out, my God. It's like a therapy session."

Getty images (2) Kelly Clarkson, Simon Cowell

The America's Got Talent judge then went on to compliment her character and thanked her for being the reason Idol became such a success.

"I remember that moment when your name was called, and I was thinking to myself, 'Thanks to you, we may have another season.' I can honestly say to you, thanks to you. You validated what we did, because if we didn't find a star, there was no point in doing these shows," Cowell said.

He continued, "I could never predict what was going to happen then. I remember talking to the record label at the time, and I said, 'I don't think you realize who you signed here. This girl has steel in her eyes.'"

"She's one of those people who, from day one, was respectful to the people who voted for her, who bought her records, who bought her tickets — and she's never lost that," Cowell concluded. "This is the Kelly you see. The Kelly you see in front of the camera is that Kelly you see behind the camera."

Former Idol judges Paula Abdul, Randy Jackson, producer Jason Halbert and friends and family of Clarkson were in attendance at the ceremony.

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The ceremony came less than two weeks after she celebrated the 20th anniversary of winning the show in its inaugural season. She marked the occasion with a post on Instagram.

"20 years ago today I won American Idol and it forever changed the course of my life. That moment was the door that opened up so much access and opportunity, and creative partnerships that I will be grateful for all of my days," Clarkson wrote in the lengthy post.

"The family and friendships I have created over these 20 years in music and tv are priceless to me," she continued. "We only get so many trips around the sun and while I am proud and feel abundantly blessed of the successes and failures that I have learned from, I am most proud and grateful for those friends that have become family, and for their arms that have held me when I needed it and their hearts that listened to me when I felt lost. Without them I would not be where I am. I would probably not be here at all."