TV presenter Caroline announced on Wednesday night (11 June) that she'd quit the X Factor spinoff show after three years of co-hosting.
Two of those years had been spent hosting alongside Olly, who left before the tenth series in order to concentrate on his music career.
Reacting to Caroline's exit, he tweeted: "Massive loss to Xtra Factor! Brought show back to life. Big shoes to fill!"
He also uploaded a YouTube video of Caroline and Olly's best moments of the 2012 Xtra Factor series.
Olly said: "Great Memories @carolineflack1 2012 xtra factor!! One of best things I've ever done."
Watch Olly and Caroline's best bits:
Caroline announced her departure in an Instagram post, which read: "After three brilliant years of hosting Xtra Factor it's time to pass the baton. It's been incredible and I'll never forget it."
Joking about an Xtra Factor skit of the past, she added: "How can I when I'm married to Louis Walsh? It's all he ever talks about at home. I wish the new team all the best and look forward to watching the new series."
She hosted the last series of Xtra Factor alongside comedian Matt Richardson, who was brought in to replace Olly.
A replacement for Caroline has yet to be announced.
As well as seeing a new co-host on Xtra Factor, this year's X Factor will feature the return of judges Simon Cowell and Cheryl Cole, who left the show in 2011. There will also be a new judge in the form of Spice Girl Mel B.
Louis Walsh, however, will bring some familiarity as he's back for his eleventh year in a row!
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