The track is certain to be at the top of the Billboard Hot 100 this week and is also on course to establish Swift as holding the record for the biggest sales debut for a digital released song by a woman in US history.
Lady Gaga currently holds the record after shifting 448,000 copies of her 'Born This Way' single in 2011.
'We Are Never Ever Getting Back Together' is taken from Swift's forthcoming album 'Red', which will feature a collaboration with UK artist Ed Sheeran when it is released later on this year.
Speaking about Sheeran in a webchat this week, Swift said: "Ed Sheeran is one of my favourite people in the world."
"He's so cool and he's such a great artist. We wrote a song while sitting on a trampoline that we loved so much that we ended up recording it as a duet."
Check out 'We Are Never Ever Getting Back Together' below: