Sir Rod Stewart congratulated Rangers for their derby win but slaughtered Alfredo Morelos for diving.
The celebrity Celtic fan watched his team lose at home to their city rivals for the first time in nine years, as Nikola Katic's second half header secured the points.
Morelos was shown a second yellow card for diving in stoppage time, and the rock star couldn't help having a cheeky dig.
He wrote on Twitter: "Congratulations to Rangers .
"Could have gone either way.
"Would someone please tell Morelos to just stand up and play football? If he must dive please go to the nearest swimming pool."
Some Hoops fans were unhappy that the singer had congratulated Rangers, continuing a tiff with elements of the support.
Earlier this month Stewart tweeted to congratulate Boris Johnson for his election win, prompting a Green Brigade banner declaring "Tories not welcome".
Sir Rod is often seen at Celtic Park for matches and mentions the club in his song 'In My Heart'.
