Brian Rasic/WireImageU2 welcomed Noel Gallagher onto the stage during their concert at The O2 in London on Monday night.
Bono introduced the former Oasis guitarist by calling him "one of my heroes."
Gallagher played the acoustic guitar and provided backup vocals for a rendition of the U2 classic "I Still Haven't Found What I'm Looking For."
Fan-shot footage of the performance has been posted on YouTube.
Bono and Gallagher are longtime friends. Gallagher was the inspiration for the song "One Step Closer" from U2's 2004 album, How to Dismantle an Atomic Bomb.
U2 has additional shows scheduled at The O2 for Thursday, Friday, Monday and next Tuesday.
Copyright © 2015, ABC Radio. All rights reserved.