Taylor Swift and Avril Lavigne are proving that things are anything but "Complicated" between the two of them, and took us back -- all the way back -- to 2002. Lavigne is the latest star to join Swift on her tour to promote her hit album 1989 to sing Lavigne's hit song "Complicated."
Afterwards Swift tweeted that she felt the song was "brilliant" and she "loves" Lavigne.
Lavigne later responded by tweeting that T-Swift rocks.
Such a Pleasure to perform "Complicated" tonight with taylorswift on her #1989 world tour! She ROCKS… https://t.co/LkTC7MVJ1d— Avril Lavigne (@AvrilLavigne) August 30, 2015