Kelly Clarkson's emotional Idol roller coaster

Kelly Clarkson was "so embarrassed" that she broke down in tears on American Idol.

The 33-year-old singer was crowned the first winner of the television talent show back in 2002 and returned to the programme, which is in its last ever series, last week (25Feb16) to perform her new single Piece By Piece. Her rendition was an emotional one, and saw Kelly stop numerous times to collect herself before she continued.

Kelly is expecting her second baby with husband Brandon Blackstock and blamed her pregnancy hormones for causing such an emotional reaction to the performance.

"I came off almost in tears for a different reason because I was so embarrassed," Kelly said during an appearance on The Ellen DeGeneres Show airing on Thursday (03Mar16). "I was like 'Oh God this is my final thing on Idol and I could not hold it together'. I was almost losing it almost the entire song.

"I was proud of myself for making it as far as I did. My husband knows me well. I came off stage and he was like don't ruin it. Don't ruin the moment. Because I was like 'it was so embarrassing'."

Even rehearsing the song earlier in the day caused Kelly to become overcome with emotion, and Kelly admits she was left crying all day.

"My one-year-old is running around the same hallway as I was 19," she explained. "He (Brandon) was there my little girl was there my little boy was like turning circles in my stomach. It was like nostalgic. It was the last time I was gonna be on Idol and it's ending. I was screwed from the get-go - emotionally, I was on a slip and slide from hell."

Kelly penned the track about her father leaving when she was just a child, and how grateful she is to have found Brandon and started a family with him.

While the song undoubtedly prompts an emotional response, with judge Keith Urban also reduced to tears by the performance, Kelly insists it's a hopeful tale as well.