Their cause wasn’t helped by an early red card for Callum McGregor – sent off for picking up a second booking in the move that led to Rangers opening the scoring through Kemar Roofe in the 26th minute.
Celtic recovered from that double whammy to level through Odsonne Edouard on the half hour but a chaotic six minute spell ended with Alfredo Morelos quickly restoring Rangers’ lead, and the hosts never looked back, adding another two goals in the second half through Roofe and substitute Jermain Defoe.
The defeat leaves Celtic a whopping 23 points behind their Glasgow rivals, who are now two games from completing an undefeated league season.
Here’s how the Celtic players rated:
5. Kristoffer Ajer - 5
Too soft defensively - ducked out the way of Morelos strike and gave Roofe too much space - but some great runs into midfield and beyond Photo: Ross MacDonald - SNS Group
6. Scott Brown - 5
Nutmegged by Morelos at Rangers second goal and failed to impact game in his final Old Firm fixture. Bowed out on the hour. Photo: Craig Foy - SNS Group
7. Callum McGregor - 2
Looked fired up early on but overstepped mark with two uncharacteristic rash challenges for early red card to leave his team up against it Photo: Craig Foy - SNS Group
8. David Turnbull - 6
Has been a stand-out for Celtic this season but not on this occasion. Struggled to affect the game, and lacked conviction in header that could have drawn 10 men level at 2-2 Photo: Craig Foy - SNS Group