The Oscar-winning actor is currently shooting Tarantino’s ninth film in Los Angeles.
Set in 1969, Leo plays Rick Dalton, a Western TV star opposite Brad Pitt’s Cliff Booth, his longtime stunt double.
Recent set photos have seen LA streets turned into their period setting, but now Leo has been snapped sporting a wig and side burns while on a lunch break.
The 43-year-old was caught holding a sandwich and wearing a white T-shirt and jeans by some trailers.
Interestingly the hair-do and stick-on side burns are different to his character Rick’s look in the first official photograph with Brad’s Cliff.
And also not the same as a recent set photo with Tarantino, sporting his usual trimmer cut.
In comparison the wig and sideburns are much more in tune with the late 1960s/early 1970s style.
Since he’s playing an older actor coming to terms with the new Hollywood in 1969, perhaps this is his character’s attempt to fit in.
He told the Hollywood Reporter: “[It’s] a story that takes place in Los Angeles in 1969, at the height of hippy Hollywood.
“The two lead characters are Rick Dalton (Leonardo DiCaprio), former star of a Western TV series, and his longtime stunt double Cliff Booth (Brad Pitt).”
“Both are struggling to make it in a Hollywood they don’t recognise anymore. But Rick has a very famous next-door neighbour…Sharon Tate.”
Margot Robbie has been asked by Tarantino to play the late actress, who was murdered while pregnant by the Manson family.
The director added: ““I’ve been working on this script for five years, as well as living in Los Angeles County most of my life, including in 1969, when I was seven years old.
“I’m very excited to tell this story of an LA and a Hollywood that don’t exist anymore. And I couldn’t be happier about the dynamic teaming of DiCaprio & Pitt as Rick & Cliff.”
Once Upon A Time in Hollywood will be released in UK cinemas on July 26, 2019.