Celtic's Europa League hopes took another blow as Celta Vigo came from behind to inflict their third straight defeat in the competition.
After an emphatic 7-1 win against Hearts, the Hoops once again showed their struggle to take their domestic dominance into European competition.
The Celtic fans were screaming for a penalty when Callum Osmond went down from a push from Javi Rueda. It was just outside the box, with the referee deciding not to award a free-kick.
Mika Baur did give them the lead just after the break as he swept home a deflected cross from Haissem Hassan.
After Liam Scales hit the crossbar, Celta hit back with a quick double.
Javi Rodriguez headed in from a free-kick, then hammered in from 20 yards to leave Celtic pointless after three games.
More to follow...
Key moments from Celtic Park....
12: BLOCK! Colby Donovan is well placed to clear Javi Rueda's cross as Celta Vigo look to open the scoring.
15: BLOCK! Mika Baur is in the right place this time to stop Iago Aspas' effort.
23: PENALTY APPEALS! Callum Osmand is pushed as he ran into the box, but the referee is having none of it. Camilo Duran is booked for his protests.
43: CHANCE! The ball falls to Osmand outside the box after Duran failed to get his shot away. He sends it well over the bar.
44: SAVE! Ferran Jutgla is denied by Sam Johnstone with half time approaching.
47: GOAL CELTIC! Haissem Hassan sends in a dangerous cross, it takes a deflection and breaks to Mika Baur to fire in.
52: CHANCE! Aleix Febas meets Sergio Carreira's low cross only to send it past the post.
63: OFF THE BAR! Liam Scales inches from doubling Celtic's lead. The defender gets his head to Hassan's cross, but it hits the woodwork.
68: GOAL CELTA! Javi Rodriguez meets the free-kick and his header can't be saved by Johnstone.
72: GOAL CELTA! A brilliant strike from Rodriguez, a nightmare for Celtic.They fail to clear the danger and he fires in from outside the box.
85: SAVE! Forrest sets up Donovan, but his effort lacks power and it's easily saved.