Katy Perry opens up on the wake-up call she had after her flop 2017 LP 'Witness' on new song 'Smile'.

The track from the pop superstar's upcoming sixth studio album recently leaked online and the honest lyrics see Katy admit to having feelings of ''rejection'' on the super-reflective song, which is classic Katy.

She belts: ''Rejection can be God's protection/Long hard road to get that redemption.''

The 'California Gurls' hitmaker - who is expecting her first child with fiance Orlando Bloom - also sings about feeling ''fake'' and failing ''the test''.

She sings: ''Goin' through motions, felt so fake, Not myself, not my best, Felt like I failed the test.''

On the upcoming track, which features a cameo from rapper Diddy, she continues: ''I'm 2.0, remodelled, Used to be dull, now I sparkle, Had a piece of humble pie, That ego trip saved my life.''

'Smile' and recent hit 'Never Really Over' are both set to appear on Katy's next record.

'Witness' sold only 900,000 copies worldwide, whilst her seminal LP's 'Teenage Dream' and 'Prism' shifted 10 million units in total.

Katy previously revealed she suffered with ''bouts of situational depression'' when her ''heart was broken'' after the mixed response from the public to 'Witness'.

She said: ''I had bouts of situational depression. My heart was broken last year because, unknowingly, I put so much validity in the reaction of the public, and the public didn't react in the way I had expected to. Which broke my heart.''

And the 35-year-old singer decided to go to the Hoffman Institute in California to give her ''a new foundation.''

She added: ''For years, my friends would go and come back completely rejuvenated, and I wanted to go, too.

''I was ready to let go of anything that was holding me back from being my ultimate self.

''Music is my first love and I think it was the universe saying, 'OK, you speak all of this language about self-love and authenticity, but we are going to put you through another test and take away any kind of validating 'blankie.' Then we'll see how much you do truly love yourself.'

''That brokenness, plus me opening up to a greater, higher power and reconnecting with divinity, gave me a wholeness I never had.

''I recommend it to everyone, my good friends and other artists who are looking for a breakthrough.

''There are a lot of people who are self-medicating through validation in audiences, through substances, through continually running away from their realities - denial, withdrawal.

''I did that for a long, long time too ... The biggest lie that we've ever been sold is that we as artists have to stay in pain to create.''