Ellen DeGeneres was like a dog with a bone, and the talk-show host wouldn't let go of the idea that Taylor Swift and High School Musical star Zac Efron are dating.

"You're both so adorable and you're adorable together. . . . You're just such a cute couple," Ellen told the two, together to promote upcoming animated movie The Lorax.

Zac: "I knew this was gonna happen."

Taylor: "I knew this was gonna happen, too. We're not, though."

But one little denial isn't enough to stop Ellen. While Taylor was talking about some of her fans crying in front of her, Zac said, offhand, "She brings a tear to my eye."

"Because y'all are a couple, that's why," Ellen shot back, grinning.

"We are not," Taylor said, sighing.

Later in the interview, which aired Tuesday (Feb. 22) on The Ellen DeGeneres Show, Taylor said, "We are not a couple. People get together when they're shooting movies, co-stars. But not like animated movie co-stars."

That made the audience laugh loudly.

Taylor added, sarcastically, "Oh my God, as we were recording our voice-overs on separate coasts, we really connected."

"Alright, we'll talk about the fact that you're a couple later," Ellen said.