The Scottish champions were embarrassed on their home turf by Sparta Prague, a team they were expected to defeated and ultimately needed to defeat in order to have any chance of qualifying for the knockout stages of the competition.
A hat-trick from Lukas Julis had the game won before Ladislav Krejci added a fourth in injury time. Leigh Griffiths netted for Celtic after coming off the bench and briefly threatened to ignite a comeback, but the home side were second best for most of the night.
They now need to win all three of their remaining games to have any chance of qualifying, though manager Neil Lennon even admits “Europe is gone”.
Player ratings scale - 10: One of best performances you've seen. 9: Outstanding. 8: Very good. 7: Good. 6: Average. 5: Poor, 4: Very poor. 3: Terrible day at office. 2: Abysmal. 1: One of worst performances you've seen.
9. MC - Tom Rogic - 5
A couple of very nice touches and created the goal for Griffiths, but he wasn't mobile enough to deal with a game like this where Celtic were struggling. Photo: Ross Parker - SNS Group
10. ML - Mohamed Elyounoussi - 5
He's been in great form lately but there was little evidence of that. Had a couple of efforts on goal and unlucky to hit the bar, but another who didn't play with the required intensity. Photo: Craig Williamson - SNS Group
11. FC - Odsonne Edouard - 5
The French striker still looks completely out of sorts. Only threatened in a couple of moments and deservedly subbed. Photo: Nikola Krstic - SNS Group
12. Sub - Leigh Griffiths - 7
Gave Celtic a spark after coming off the bench and netted for the hosts. Photo: Craig Foy - SNS Group