It was such an unexpected result that even Rod Stewart burst into tears.
The rock star was caught on television crying at Celtic Park after the Scottish champions beat mighty Barcelona in the Champions League on Wednesday.
There had been a late scare when Barca star Lionel Messi scored in the 90th minute, but Celtic held on to mark its 125th anniversary with a memorable 2-1 win.
The victory puts Celtic on course to advance from the group stage to the knockout phase. Neil Lennon's side is two points behind Group G leader Barca.
Stewart is one Celtic's most devoted, and famous, supporters and makes mention of his love for the club in his hit song ''You're in My Heart.''