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Ross Gellar is truly a thing of the past as David Schwimmer transforms into Robert Kardashian.

The former Friends star is playing Kris Jenner's late husband in American Crime Story: The People V OJ Simpson, and he's already making physical changes to fit the part.

The actor was spotted on set with the lawyer's trademark grey flick at the front of his hairdo, with a few white strands boldly showing up amongst the rest of his jet black locks.

(Image: Barcroft)

David looked serious and focused as he took a walk, looking smart in grey trousers and a purple checkered shirt.

After dying his hair, it's clear the star is determined to look the part - and he's even been getting tips from Kris Jenner as he seeks to deliver a stellar performance.

He recently revealed the Kardashian family matriarch was "very generous" when it came to giving him her advice and time.

(Image: Barcroft)

He told E! News: "I was lucky enough to speak with Kris for a few hours. She was very generous with her time, just telling me about who Robert was."

However, the star admitted he didn't think Kris had much of a say in the casting of her role in the movie - Selma Blair will take on the part - but praised her for the help she's provided.

(Image: JPI Studios / Barcroft Media)

He added: "I highly doubt it, but she was very generous with her time and spoke very highly of Robert...

"I'm excited to explore that relationship with Selma. She's fantastic."