American Idol: Shawn Robinson forgets the lyrics during All-Star Duets and ...

It was the worst possible time to forget the words.

As the first half of American's top 20 performed on Sunday's episode, Shawn Robinson, 21, left an awkward silence as he totally forgot his lyrics – ending the night of All-Star Duets as one of three going home.

Shawn was performing with Elle King, while the others helping with all-star duets included Jason Mraz, Pat Benatar, Shaggy and Brett Young.

Lyrics lapse: Shawn Robinson forgot the lyrics while performing during the All-Star Duets episode Sunday of American Idol on ABC

Lyrics lapse: Shawn Robinson forgot the lyrics while performing during the All-Star Duets episode Sunday of American Idol on ABC

The hardware store assistant was immediately worried at performing Creedence Clearwater Revival's Proud Mary, admitting of the upbeat rocker: 'It's not what I really do.'

Those fears only escalated when Elle, 29, made a last-minute decision to slow down the version of the song compared to what they had rehearsed.

'Thirty minutes ago I found out that we are completely changing the tempo of our song. It's really scary,' he said before taking the stage.

His fears were realized when he forgot the words at a key point, leaving an awkward silence for a whole line.

Song change: Elle King made a last-minute decision to perform a slowed down version of Creedence Clearwater Revival's Proud Mary

Song change: Elle King made a last-minute decision to perform a slowed down version of Creedence Clearwater Revival's Proud Mary

Elimination episode: Katy Perry, Luke Bryan and Lionel Richie determined which seven finalists of the 10 who performed would advance

Elimination episode: Katy Perry, Luke Bryan and Lionel Richie determined which seven finalists of the 10 who performed would advance

'That stuff happens onstage,' Elle insisted afterward, with the judges also trying to ease his nerves.

'I'm in the multiple mistakes a night category,' Luke Bryan, 42 told him, while Lionel Richie, 69, insisted: 'I love the way you recovered.'

'That was a pro move,' Elle told him of the way he pressed on despite the obvious mishap. 'I'm so proud of you, man.'

Awkward silences: Shawn after forgetting the lyrics was critiqued by the judges as host Ryan Seacrest stood next to him

Awkward silences: Shawn after forgetting the lyrics was critiqued by the judges as host Ryan Seacrest stood next to him

Luke had insisted he should be 'proud of what you just did,' telling him: 'It was a great vocal performance up there.'

'I went up there and did my best. I had a slip-up... it's up to the judges now,' Shawn said before the big decision.

Shawn ended the night one of three going home, along with New York subway singer Bumbly, 27, and 23-year-old Kate Burnette.

Duet performances: Kate Barnette, Walker Burroughs, Riley Thompson, Uche, Madison VanDenburg, Shawn, Ashley Hess, Bumbly, Laci Kaye Booth and Laine Hardy performed duets before three were sent home

Duet performances: Kate Barnette, Walker Burroughs, Riley Thompson, Uche, Madison VanDenburg, Shawn, Ashley Hess, Bumbly, Laci Kaye Booth and Laine Hardy performed duets before three were sent home

Kate's biggest clue that she was going home was the way the judges spent almost all of their commentary gushing over her star, Pat Benatar.

'It was wonderful to see her onstage,' Lionel said of the legendary rocker after their performance of Heartbreaker. 'She was standing still and giving us attitude.

'I can't teach that to you. You take that, put it in your memory bank and use it for the rest of your career.'

Rocking out: Kate performed with rock legend Pat Benatar

Rocking out: Kate performed with rock legend Pat Benatar

Bumbly, meanwhile, was shown in tears even before she was known to be heading home, with her star, Shaggy, hugging her and saying: 'You were born to do this.'

They performed Shaggy's Angel – with the star changing sections to recite her name – and he predicted beforehand: 'I think she'll win them over with that big smile, that bubbly personality – and that amazing voice.'

But again, a lot of the praise was for the star – real name Orville Richard Burrell – with Luke saying: 'That's my first Shaggy concert! If you can't have fun up there with Shaggy then you've got serious problems.'

Fun song: Shaggy and Bumbly got the crowd going during their duet

Fun song: Shaggy and Bumbly got the crowd going during their duet

Lionel had insisted the decision would be the 'hardest thing we've ever done,' and told the three heading home: 'Use this night. God has blessed you with an amazing launch.'

Laci Kaye Booth had been the first sent through to the next round – a clear frontrunner from the night.

'I don't want to play favorites but … but fill in the blank,' Katy Perry told the 34-year-old contestant, claiming it was like a performance at the Grammys.

Sent home: Bumbly was sent home while Laci and Laine advanced

Sent home: Bumbly was sent home while Laci and Laine advanced

'I mean, from the moment you walk onstage, you sprinkle stardust everywhere,' Katy insisted.

Laci performed Mercy with her own idol, Brett Young, telling him she was 'a little starstruck' and 'obsessed' with his music.

'I am fangirling for sure,' she admitted, saying after the performance: 'I've been obsessed with him and his song Mercy for forever, so it was a dream.'

Instant chemistry: Brett Young performed with Laci and they were praised for their chemistry

Instant chemistry: Brett Young performed with Laci and they were praised for their chemistry

Lionel called it 'an incredible performance' and sad the chemistry was real.

'I actually thought I was watching a serious love affair happening up on that stage because it was delivered so well. This is gonna be big for you,' he predicted.

'When you sing it just hits you right in the heart,' Luke agreed.

The host: Ryan Seacrest hosted the two-hour episode filmed at the Wiltern Theatre in Los Angeles

The host: Ryan Seacrest hosted the two-hour episode filmed at the Wiltern Theatre in Los Angeles

'Especially when you sing a song about heartbreak – you make it the worst heartbreak ever. And for some reason, people love that.

'It's just an amazing gift you have.'

Ashley Hess, 27, was the next through having even wowed her star, Jason Mraz, with her

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