Carly Simon joined Taylor Swift on stage Saturday night (July 27th) at Gillette Stadium in Foxborough, Mass. for a surprise guest appearance.
The two performed Simon's iconic hit "You're So Vain" for the sold-out crowd of more than 55,000 fans.
The clip below includes performance footage, backstage interview and BTS footage.
Taylor was in Foxborough over the weekend playing to more than 110,000 fans at back-to-back sold out shows at Gillette Stadium as part of her blockbuster The RED Tour.
The RED Tour is currently playing 66 shows (including 13 stadium stops) in 47 cities in 29 states and 3 provinces in North America spanning six months in 2013.
Taylor will take The RED Tour to Australia and New Zealand later this year, performing stadium shows in Sydney, Melbourne, Brisbane and Perth, as well as arena dates in Auckland. Taylor will be the first solo female artist in twenty years to undertake a national stadium tour of Australia.