As two top tier models, she and Gigi Hadid are professional competitors.

And now Lisa Rinna's daughter Delilah Belle Hamlin, 19, is dating her rival's assistant Cully Smoller, according to UsWeekly.

'They are very casually dating and hooking up,' a source told the gossip magazine.

New love: Lisa Rinna's daughter Delilah Belle Hamlin, 19, is dating her rival's assistant Cully Smoller, according to UsWeekly. Seen together in September 2017

The eldest daughter of Mad Men actor Harry Hamlin was photographed with the actor/assistant in September last year.

But on Tuesday the relationship was confirmed to UsWeekly.

Delilah is a frequent guest on her Days Of Our Lives actress mother's reality TV show, Real Housewives Of Beverly Hills.

Romance: The eldest daughter of Mad Men actor Harry Hamlin was photographed with the actor/assistant in September last year

Photo evidence: She smiled as she wrapped both arms around the man

In a January episode of the show, Delilah admitted to learning oral sex technique at age 12 from her mother's sex guide, The Big Fun Sexy Sex Book.

In an embarrassing on-air admission, Delilah said 'I was like 12 when I saw this. It literally teaches you how to give head.'

'Very precisely,' added her 16-year-old sister Amelia.

'If you're gonna learn you better learn it right,' Rinna replied.

TMI: In a January episode of Real Housewives Of Beverly Hills, Delilah admitted to learning oral sex technique at age 12 from her mother's sex guide, The Big Fun Sexy Sex Book