Conor McGregor announced his retirement from mixed martial arts last week, but that hasn’t stopped him from prolonging his rivalry with Khabib Nurmagomedov.

Khabib, who defeated McGregor at UFC 229, posted a rather harmless photo last week thanking his fans for their support and teasing a return to the octagon.

This caught the attention of McGregor, who took a shot at Khabib on Twitter by referencing the all-out brawl that erupted after their October fight and the subsequent $500,000 fine Khabib received for his role in the bedlam at T-Mobile Arena.

Khabib, who jumped the cage and attacked McGregor’s camp after his fourth-round submission victory over the The Notorious, didn’t accept the Twitter jab laying down. Instead, the undefeated UFC lightweight champion fired back at his rival Sunday by pointing out the “honor” McGregor lost in defeat.

UFC president Dana White recently said Khabib will return in September. It’s possible Khabib will face the winner of next month’s Max Holloway vs. Dustin Poirier bout, but maybe we shouldn’t rule out an eventual rematch with McGregor given the obvious interest that fight would generate.

Thumbnail photo via Noah K. Murray/USA TODAY Sports Images