Jessica Simpson's "feet were sweating" during her live performance on 'American Idol'.

The 44-year-old pop star performed on TV for the first time in 15 years on 'American Idol', and Jessica has confessed to feeling very nervous ahead of her recent appearance.

The blonde beauty told 'Extra': "Oh, my God, I was dying.

"I can't even tell you how long it's been since I've been that nervous. Like, I had to put hairspray on my feet to stand still, like, not that it actually keeps me put, but, like, my feet were sweating. I'm like, my feet don't sweat.

"I just kept telling myself, 'Do not cry. Do not cry. I know this is a big moment … do not cry.' And then I see my dad, like, up in the corner and I'm like, 'Ah, I'm going to cry. I'm going to cry. Do not cry. Just sing your songs. Just sing your songs.'"

Jessica felt "very vulnerable" singing songs from 'Nashville Canyon, Part 1', the EP that she released in March.

The pop star explained: "[15 years is] a really long time, and, like, the last time was a Christmas song, so that's easy.

"So, this is my new EP 'Nashville Canyon Part 1', I mean, part two comes in the summer, but it is so much a part of my soul, and so to sing a song off of that I felt naked, to be honest, like, it was very bare and raw and very vulnerable."

Jessica believes she's reinvented herself as an artist in recent times.

Explaining the inspiration behind her new music, Jessica said: "It was really like I made a Spotify playlist of just music that I like, and it was not really any of the music that I've done before, because for me that was what people told me to do.

"And I wanted to do something I was going to tell myself that I needed to do and felt right within my soul, so this playlist I would take into with songwriters and we'd sit there and they'd pick a song from the playlist and we'd kind of like vibe off of it."