The rumoured couple was first linked over the summer after taking a vacation to Greece, and last week (ends November 29), Zendaya jetted out to Sydney, where they were both honoured at GQ Australia's Men of the Year Awards.
In the lead up to Thursday's prizegiving, they were spotted hanging out together, and even spent time with Jacob's parents.
However, the 22-year-old actor has since brushed off the relationship gossip, claiming he has a special bond with the whole cast of hit drama series "Euphoria".
"She's like my sister," he told GQ Australia. "Zendaya is an amazing creative, you know? She's super dope to work with. She's an incredible artist and a very caring person to all of us (castmates). But we're all really close. There is not one weak link in that show."
Continuing to gush about his TV colleagues, Jacob added, "We've spent so much time together and everyone is just so cool to work with."
"(Creator) Sam Levinson is just a genius and working with him, it was just like electricity all the time. I was in awe. Like a kid in a candy shop."