O'Neill, now in charge at Sunderland, watched every minute of the match where Barcelona were defeated 2-1 despite enjoying 88% of the possession. O'Neill said:
"I didn't realise until now that there was only something like 11% possession for Celtic so that is absolutely phenomenal to score two goals from that.
"I watched the game through and through and I thought it was just a magnificent effort by a great club.
"I saw Rod Stewart in tears, and it was a great, great effort - to beat Barcelona was fantastic."