It was only a matter of time before Katy Perry reacted to Calvin Harris' Twitter rant about his ex-girlfriend Taylor Swift — and it was definitely worth the wait!

After calling out the "Blank Space" singer for "trying to tear" him down, Katy showed her support for the British DJ by going way back into her social media history and throwing some subtle shade at the pop star.

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"Time, the ultimate truth teller," the 31-year-old pop star retweeted from May 2015, reminding fans of her own feud with the blonde beauty.

katy perry taylor swift getty

In 2014, Taylor revealed in an interview with Rolling Stone magazine the inspiration behind her hit single "Bad Blood," leading many to believe she was talking about Katy.

"For years, I was never sure if we were friends or not," she said. "She would come up to me at awards shows and say something and walk away and I would think, ‘Are we friends, or did she just give me the harshest insult of my life?’"

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She continued, “She did something so horrible. I was like, ‘Oh, we’re just straight-up enemies.’"

Following the interview, Katy went on to tweet, "Watch out for the Regina George in sheep's clothing."

Now, only time will tell if Taylor will respond to these new accusations. For a look at more heated celeb feuds, check out the gallery below!