By Selena Hill (staff@latinospost.com) | First Posted: Oct 01, 2013 02:51 PM EDT

Katy Perry's grand finale at the 2013 iTunes Festival went out with a roar.

The 28-year-old pop star took the stage at The Roundhouse in London Monday night to close the star-studded month-long concert series with a 45-minute set she infused with smash hits like "Teenage Dream" and "I Kissed A Girl," as well as four new songs from her upcoming fourth studio album, "Prism," which is scheduled to drop Oct. 22.

Katy opened the last 2013 iTunes Festival show with her new single "Walking On Air," a 90s house-styled track that was released on iTunes this week, reports DirectLyrics.com. The crowd then enjoyed singing along to her pop gems like "California Gurls" and "Firework."

Halfway through the concert, Perry was joined on stage by rapper Juicy J for her performance of "Dark Horse."

For an extra treat, Katy debuted a never-before-heard song from "Prism" called "By the Grace of God," to the delight of her 3,000 plus fans in the crowd, and the millions watching from their iOS devices online. In the beautiful ballad, the California native opens up about her split from her ex-husband Russell Brand, reports Mirror.co.uk.

For the last song, Katy turned the volume up for "Roar!," her latest global chart-topping hit. To finish her set, a makeshift boxing ring was brought onto stage and she completed the performance with a rope skipping routine without missing a step.

Watch Katy Perry's full performance below:

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