Joining Rangers means that a player is automatically disliked by Celtic fans, but Gers midfielder Joey Barton certainly seems intent on making sure that nobody on the green half of Glasgow likes him much.
The 33-year-old, who joined Rangers on a free transfer last month after helping Burnley win Premier League promotion this past season, made headlines at the weekend after claiming that Scott Brown was nowhere near his level.
Two days on and the former Premier League man has now aimed a barb at Celtic boss Brendan Rodgers, questioning his managerial record.
The ex Liverpool and Swansea City manager was named as Ronny Deila's replacement at Paradise this summer, restoring a huge sense of optimism at the club following an underwhelming couple of years in which Celtic failed to reach the Champions League.
It is the 43-year-old's fifth club, and Rangers man Barton suggested that Celtic fans' reaction to the appointment was a little OTT considering he is yet to win a major title in management.
Barton's medal collection is hardly bulging, having won the Championship on two occasions, and some Hoops fans reminded him not to throw stones in glass houses.
@DarrenBSCooney The only thing Barton has "won" was a tag when he came out of prison after his assault conviction !— Sunny Bhoy (@Tenerifetim10) June 13, 2016
@Record_Sport smartest bit of advice anyone should give Barton is to keep his mouth shut, this isn't England.— Martino (@MartinoHarley) June 13, 2016
@Record_Sport Bad season for Celtic would be going into administration & Liquidation. But then they could Phoenix & start off in bottom tier— Binderdunnit (@connollybhoy) June 13, 2016
Barton banging on about Rodgers cabinet while his in empty!— Vinny (@VinnyCSC) June 13, 2016
Hope nobody at Celtic even mentions Joey Barton in any interviews to come. Absolute irrelevance.— Stepherus Snape (@SO_1888) June 13, 2016
Leave Joey Barton alone, he's a Celtic fan, that's why he cannie stop mentioning us.— The Captain (@BigLinton) June 13, 2016