Police Scotland said on Monday they are looking into alleged online racial abuse of Rangers' Colombian striker Alfredo Morelos after he scored in Sunday's 1-1 draw with Celtic.
Morelos equalised in the 38th minute with his first goal in 13 Old Firm game appearances as Scottish champions Rangers extended their unbeaten league run to 33 matches this season.
"An investigation is under way after we received a number of complaints regarding an offensive social media post and enquiries are ongoing," Police Scotland told British media.
The incident came after Rangers midfielder Glen Kamara complained of being racially abused by Slavia Prague centre back Ondrej Kudela in their Europa League match on Thursday, which UEFA is investigating.
Rangers captain James Tavernier said all Black players in the team had been abused on social media this season.
"We took a knee to send out a message but we believe that message isn't strong enough. We wanted to send out a strong message and it was an easy decision," he said.
"But I feel confident saying that all our Black players have received racial abuse this season. That's from social media platforms and this is a key message to them. Action has to be taken - enough is enough."
(Reporting by Rohith Nair in Bengaluru, editing by Ed Osmond)
