Official Chart Flashback 2013: Katy Perry's Roar lets the light in for a massive debut at Number 1

Katy Perry's biggest UK hit debuted at Number 1 on the Official Singles Chart this week nine years ago.

She's got the eye of the tiger. Katy Perry was calm, composed and most of all confident as she let the light in on the first single from her third album, Prism.

That single had a lot to live up to. Her previous record - 2010's Teenage Dream - had exceeded all expectations, and then some. With its candy-coated, bubblegum pop aesthetics, it birthed seven UK Top 10 hits including one Number 1 (California Gurls). In Katy's native US, it performed even better; with five consecutive Number 1 singles, she's only the second-ever artist to achieve this from one album (the other? Michael Jackson with Bad). In short, it had made one of the most famous - and successful - pop stars of the modern era.

There was just one question... how do you follow that?

The answer turned out to be; reuniting with your crack team of pop hitmakers (in this case producers Max Martin, Dr Luke and Cirkut alongside songwriter Bonnie McKee) for an anthem all about self-acceptance, learning to love yourself and, above all, roaring.

MORE: Katy Perry's Official UK Chart history in full

It turned out to be a recipe for continued success. Roar debuted at Number 1 on the Official Singles Chart, replacing Ellie Goulding's Burn and becoming Katy's fourth UK chart-topper. Shifting a massive 179,000 copies in its first week, Roar is Katy's fastest-selling song.

Spending a total of two weeks at the chart summit, Roar is still Katy's biggest song overall in the UK, with chart units totalling 2.4 million across all formats, including 163m streams. It's also her biggest-selling single ever too, with 1.14 million downloads to date.

Roar also debuted at the top of the US charts too, where it was part of a hotly-contested (and very last minute) chart battle with Lady Gaga's Applause. The stakes weren't as high in the UK, however, as Applause had received a very quick release four weeks earlier, debuting and peaking at Number 5.

Prism would contain a further Top 10 single in the form of gothic banger Dark Horse featuring Juicy J, plus Top 40 hits Unconditionally, Birthday and This Is How We Do.

Elsewhere in the chart that week, there were new entries from You Me At Six, debuting at Number 11 with Lived A Lie and brand-spanking-new girl group Neon Jungle who were straight in at Number 12 with debut stomper Trouble. Indie pop trio London Grammar also earned their first (and, so far, only) Top 20 hit this same week, when Strong debuted at Number 17.

At 39, Californian rock band Starship saw their 1987 Number 1 Nothing's Gonna Stop Us Now return to the Top 40 thanks to its feature on a TalkTalk TV ad campaign that aired during The X Factor one week prior - shooting up by a very impressive 1,520% week-on-week.

Just outside the Top 40, original Sugababes members Mutya, Keisha and Siobhan attempted a comeback as MKS, but their first and only release under that moniker, Flatline, dropped in at Number 50 after being released just two days prior.