A second source confirmed to In Touch that one morning in September, a driver arrived to collect Jamie, 45, from the Trump Soho Hotel to take him to the set of his new film, 'Annie' — but Katie stepped into the limo instead.
Katie was first spotted partying with Jamie in July at the star-studded Night Of Legends party in the Hamptons.
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Katie and Jamie partied together at a charity bash in the Hamptons in July
Another partygoer said Katie - who divorced Tom in 2012 after six years of marriage - began dancing with Jamie when Lenny Kravitz took to the stage and was also reportedly seen sharing his drink.
However, a rep for the 34-year-old actress insisted the pair are still just 'friends'.
For more on Katie and Jamie’s new romance, pick up this week's issue of In Touch, on newsstands now
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Chris Evans & Minka Kelly(02 of14)
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Taylor Lautner & Marie Avgeropoulos(03 of14)
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Freddie Prinze Jr. & Sarah Michelle Gellar(05 of14)
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Carey Mulligan & Marcus Mumford(06 of14)
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Hilarie Burton & Jeffrey Dean Morgan(07 of14)
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Gwyneth Paltrow & Chris Martin(08 of14)
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James Lafferty & Eve Hewson(13 of14)
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Jesse Eisenberg & Mia Wasikowska(14 of14)
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The stars have reportedly been dating since July 2013. (credit:Getty)