Shay Logan has criticised Scott Brown pictured in an Aberdeen shirt and tweeted: "You can't polish a turd".
The former Celtic captain joined the Pittodrie club on a free transfer this summer as player/coach to Dons boss Stephen Glass.
The 35-year-old midfielder modelled the Aberdeen top as the Granite City club launched their new home kit on social media.
Under the photo of Brown in the red shirt on Aberdeen's official Twitter account, former Dons defender Logan, replied: "What's the saying, you can't polish a turd," which was followed by a 'pile of poo' and 'tears of joy' emojis.
In 2014, Brown and Celtic backed Aleksandar Tonev when then Aberdeen right-back Logan accused the Celtic player of racial abuse with the Bulgarian consequently banned for seven matches.
After joining Hearts until the end of the season in April, Logan insisted that there was ill-feeling between him and Brown over the incident.
He said: "It's not that we didn't get on – he played for Celtic, I played for Aberdeen, there was rivalry on the pitch. He wanted to win, I wanted to win."
Logan recently poked fun at Celtic's ongoing pursuit of a new manager on his Twitter account, with a mocked-up photo of him holding a green and white scarf above his head at Parkhead and saying: "Thought I'd make my first role in management a small one and build it up from there. I can't say I'm happy for the role but hey a job's a job no one else wanted it."
On his official Instagram account, Brown wrote: "So the new beginning starts as player/coach at @aberdeenfc
"I'm looking forward to the challenges in front of us all. Also I can't wait to get fans back into the stadiums."