Guitarist Duff McKagan tweeted this week to say that Young had greeted the band at the airport, sending the rumour mill into overdrive and last night they made Sydney fans very happy.
Young jumped up with the band to cover AC/DC classics Riff Raff and Whole Lotta Rosie with the band later posting footage on Twitter.
This is the second time Young has jumped up on stage with the band in the last 12 months. He played the same two songs with them at Coachella last year.
Frontman Axl Rose fronted AC/DC at the end of their tour last year after Brian Johnson bowed out.
Guns N’ Roses are due to perform another show in Sydney tonight and no doubt fans will be hoping for a repeat of last night’s Young appearance.
Check out the full tracklist from last night plus footage of Young’s guest spot below.
— Guns N' Roses (@gunsnroses) February 10, 2017