Katy Perry cited performing 'Firework' at a charity fundraiser with an autistic fan as her career highlight.

The 28-year-old singer shared the stage with Jodi DePiazza, 11, at a taping of Comedy Central's 'Night of Too Many Stars' last year, where Jodi played the piano and sang with Katy, who classed it as the most important performance of her life.

Speaking at the ASCAP I Create Music Expo, Katy said: '''Firework' is the most important song I've written. Performing it with an autistic girl accompanying her on piano and vocal harmony at a fundraiser was the most important performance of my career.''

Katy also spoke of her plans for her upcoming third album, saying that she will collaborate with producers and songwriters such as Max Martin and Dr.Luke on the album, both of whom previously worked with her on 'Teenage Dream''.

She said: ''Max and Luke push me the most. As a team we have certain strengths. With Max, it's melody choices, Luke is production and I'm topline and melody.

''When I put myself on a timeline, when I tell the record company when I want to release the album, that's when the race starts. That's when I put pressure on myself.''