A concert uniting a music icon and her avid fan has inspired millions. Once again belting out to the world her appalled feelings for a certain someone, Carly Simon is welcomed by Taylor Swift on stage for a duet of "You're So Vain".

Dubbed as the "original breakup anthem", Swift introduces her very special guest by letting the crowd wonder who the song was all about. Known to write heart wrenching and angsty breakup songs herself, Swift's concert reached a greater height when infused with 1970s drama.

Expectedly, Swift audience in Foxborough, Massachusetts, a stop of her Red Tour, went wild as the duo sang the vengeful song. After their duet, Swift was left reeling from such a powerful performance. In fact, the 23-year-old singer-songwriter later revealed to her Twitter followers just how delighted she was of the experience.

In her Twitter account, Swift tweeted, "Got to sing 'You're So Vain' with Carly Simon at Gillette Stadium tonight!!!!!" Then, she added, "Unreal. I could not possibly look up to her more."

In a backstage interview with Simon, which would air Monday on "Good Morning America," Swift called the performance "one of the most special nights of the tour."

"Once we get out there and we have 55,000 people in a sing-along it's just going to be like karaoke night in the stadium. Every girl out there will be thinking of someone when we're singing," Swift said.

Still dazed with the opportunity granted to sing with her idol, Swift stated, "When I heard 'You're So Vain' I just thought that is the best song that has ever been written." She further claimed, "That is the most direct way anyone has ever addressed a breakup. It's amazing."

Asked on her opinion of such a hit single, Simon shared, "It's a song that really sort of developed that style of mine". She added, "A lot of it was not knowing that I developing that style because lot of things happen by accident."

After their performance, Simon said, "It was just so wonderful that I just want to do it again." She also said that, "[Taylor] was so great, and she really led me through my own song, and she was just so loving of the whole thing, and we loved each other and we moved together in a part. It was dramatic, it was great."