Britney Spears and Sam Asghari arrive at the Los Angeles premiere of "Once Upon a Time in Hollywood," at the TCL Chinese Theatre, Monday, July 22, 2019. (Photo by Jordan Strauss/Invision/AP)

Britney Spears and Sam Asghari made their red carpet debut as a couple on Monday night at the "Once Upon A Time in Hollywood" premiere in Los Angeles.

Spears and her 25-year-old personal trainer looked loved up as they walked the red carpet.

Sharing some pictures to Instagram, Spears captioned it: "Our first premiere @samasghari (sic)"

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@onceinhollywood with the lioness @britneyspears

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Asghari also shared a picture from the premiere, writing alongside it: "@onceinhollywood with the lioness @britneyspears (sic)"

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Once up on a time in Hollywood ♥️♥️

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Spears stunned in a red mini dress, accessorised with a silver choker necklace while Asghari wore a sharp beige suit and a black tie.

Spears's relationship with Asghari has gone from strength to strength as of late after the duo met on the set of her "Slumber Party" video.

Explaining how they first met, she said: "We were doing the scene where I was doing the walk scene through the hall to go through the door to go to the bedroom and we were sitting there and waiting and waiting together for like 20 minutes at a time. We were having to be literally stuck there together, so we were basically forced to talk to each other ... I kept his number, and it was so weird – it was like five months later, and I found his number in my bag. I was like, 'He is really cute. This guy is really cute'. So then I called him, and ever since then ... He is just a really fun, funny person."

Spears previously confessed Asghari inspired her to be better and made her feel "like the luckiest girl in the world".

She said: "Every day he inspires me to be a better person and that makes me feel like the luckiest girl in the world!! (sic)"