'90 Day Fiancé' Star Sophie Sierra, 'Bachelorette' Alum Chad Johnson Fuel Dating Buzz

Bachelor Nation vet Chad Johnson's looking to score outside his TV franchise -- we got vid of the reality star getting tight with Sophie Sierra from "90 Day Fiancé."

We're told the 'Bachelorette' alum -- who emerged as the villain on JoJo Fletcher's season -- cozied up to Sophie while attending a recent Yung Bleu concert in Santa Ana, CA.

Fans of '90 Day' will remember Sophie from season 10 of the TLC hit, where she had a tumultuous relationship with Rob Warne ... who she was on-and-off with up until this past June.

It seems she and Rob are off-again, as we're told Sophie and Chad showed up at the Yung Bleu show together last weekend, and were flirting the entire evening.

Our sources say CJ and Sophie left the venue together ... for whatever that's worth.

The reality TV stars aren't hiding their connection either -- they've since uploaded a playful TikTok poking fun at Chad's 'Bachelorette' roots.

In the video, Chad hands Sophie a rose ... but he almost immediately tosses it away when she doesn't look too excited by the gesture.

We reached out to Chad and Sophie to get some clarification on the nature of their relationship, but haven't heard back.