The rumored romance between Niall Horan and Hailee Steinfeld continues to heat up.

Steinfeld and the One Direction member got extra close during a Backstreet Boys concert in Las Vegas Saturday night, further fueling dating rumors. A fan who was also at the event shared videos of the duo dancing and singing along with the popular boy band.

The series of clips showed Horan and Steinfeld having fun as they stood in the Axis Theater's VIP section at Planet Hollywood Resort and Casino. At one point during the concert, singer A.J. McLean was even seen approaching Horan and singing with him.

For the casual outing in Sin City, the British crooner wore a plaid shirt and jeans while his rumored girlfriend rocked a plunging top and jeans.

Horan and Steinfeld had been the subject of dating rumors since last year due to their close friendship. Although they were seen having what appears to be a date night, an insider told PEOPLE that they are not yet officially dating. The "True Grit" actress recently split from her longtime boyfriend and it looks like she is not rushing to get into another relationship.

"She's not actively pursuing anything," the source stated. "Niall is really into her but she's unsure if she wants to get into something new right away."

It's worth noting that this is not the first time Steinfeld and Horan have been spotted in public together. The "Pitch Perfect" star and "Slow Hands" singer were previously photographed at the American Music Awards in Los Angeles last November. He also shared a heartfelt birthday greeting for her on Instagram in December, calling her "the loveliest person on the planet."

Steinfeld was believed to be in a relationship with social media personality Cameron Smoller.