Romance is reportedly brewing between Zac Efron and “The Vampire Diaries” star Nina Dobrev. Both actors have been friends for a couple of years now, but for eagle-eyed fans, their unusual closeness of late might mean something else.

Recently, Efron and Dobrev shared a workout video together as part of Efron’s new workout and interview YouTube series “Gym Time.” The video showed the bubbly duo having a whole lot of fun as they tried to do some intense workouts together.

In between the hard slog, Efron also talked to the Les Mills x Rebook ambassador about random things. “Another big part of working out is the community of it and going to workouts with friends and having that accountability,” Nina said. “It’s like, what’s something that we all love to do? I love to hang out with friends, and sometimes we do it at the gym,” Efron replied.

While their conversation seemed casual at first, fans noticed how everything changed when Efron started to ask Dobrev one particular question. The 30-year-old actress was trying to keep up with Efron’s workout when he had her answer some questions, starting off with what her favorite piece of clothing was while she was in a cryo chamber.

“My lingerie,” Dobrev replied. Efron’s face suddenly turned red and seemed not to know how to respond to his celebrity guest’s answer. A few seconds later, he moved on to a different topic.

That particular moment sent fans into a frenzy, with some immediately taking to Twitter what they thought about the exchange. “Just go and support this masterpiece,” one fan tweeted. “Maybe I’m overreacting but djdbdjsjjs the way that Zac looks at Nina #thedobreveffect jumped out and is playing so hard,” another fan tweeted.

Many were also surprised to know that Efron and Dobrev are friends, with some speculating that Efron might have only said that to avoid romance rumors right off the bat. Before Dobrev’s appearance on Efron’s show, Efron announced on Instagram that his “friend” Dobrev would be his first celebrity guest.

Although many are shipping the two, the truth is that Dobrev and Efron are really just friends. It’s not clear when their friendship started, but back in 2010, they were photographed watching a basketball game together. They were also spotted together in Atlanta during Dobrev’s “The Vampire Diaries” days, playing bowling with Julianna Hough, who happens to be Efron’s co-star on “Dirty Grandpa.”

Efron is currently not dating anyone, while Dobrev is reportedly dating Grant Mellonand. Back in February, the actress was caught passionately kissing her rumored beau at the Super Bowl.

Oscars 2014 Red Carpet: Zac Efron BEST: Zac Efron looks handsome in his suit at the Oscars heading into the Dolby Theatre. GettyImages