Looks like Katy Perry is willing to end the bad blood with Taylor Swift soon, on one "tiny" condition: an apology from the "Blank Space" singer.

On Saturday, Perry caused frenzy on Twitter when she answered a fan question on a possible collaboration with Swift.

A user asked, "Will you collab with Taylor Swift?" To which she responded, "If she says sorry, sure!"

@HerWonkEye @katycatsophia @camilasviews if she says sorry, sure!

— KATY PERRY (@katyperry) September 10, 2016

The two pop stars used to be friendly, not until things got ugly back in 2014. In an interview with Rolling Stone, Swift hinted that her song "Bad Blood" was about a fellow singer.

"She did something so horrible," Swift said. "I was like, 'Oh, we're just straight-up enemies.' And it wasn't even about a guy! It had to do with business. She basically tried to sabotage an entire arena tour. She tried to hire a bunch of people out from under me."

Fans are quick to theorize that Swift was referring to Perry. According to reports, the "Roar" singer allegedly hired Swift's dancer in the middle of their tour to be on her team instead.

However, no confirmation has been made whether the song is indeed about Perry.

Following Swift's interview with the Rolling Stone, Perry tweeted, "Watch out for the Regina George in sheep's clothing." And in 2015, Perry had an interview with Billboard and said, "If somebody is trying to defame my character, you're going to hear about it."

Watch out for the Regina George in sheep's clothing... — KATY PERRY (@katyperry) September 9, 2014

Things only seem to get worse as Perry tweeted a GIF of Democratic Presidential candidate Hillary Clinton after her name was mentioned by Calvin Harris in his Twitter spree about his ex-girlfriend, Swift.

Swift hadn't responded to the "Rise" singer's tweet but it is an obvious fact that a collaboration between the two would be something big. Can fans still get to hear these two on a project together? Only time can tell.