Petr Yan was happy to hear Dustin Poirier refer to him as the best boxer in the UFC. What's more, the interim bantamweight champ took the opportunity to fire another shot at Conor McGregor.Yan and McGregor have been going back-and-forth as they both claim to be the best pound-for-pound pugilist among MMA fighters. 'No Mercy' seems to have found a supporter in McGregor's bitter rival Dustin Poirier.The Russian star shared a video of Poirier saying Yan is the best boxer in the UFC. To make sure his message reached McGregor, Yan tagged the Irishman and wrote the caption:"Obviously @DustinPoirier understands boxing better than @TheNotoriousMMA"Petr “No Mercy” Yan@PetrYanUFCObviously @DustinPoirier understands boxing better than @TheNotoriousMMA 😁 twitter.com/mmafighting/st…MMAFighting.com@MMAFightingWho's the best boxer in the UFC?@DustinPoirier tells @arielhelwani it's @PetrYanUFC, not Max Holloway 🥊 #TheMMAHour▶️ youtu.be/QzPig8VvdOU2:42 AM · Nov 16, 202174654Who's the best boxer in the UFC?@DustinPoirier tells @arielhelwani it's @PetrYanUFC, not Max Holloway 🥊 #TheMMAHour▶️ youtu.be/QzPig8VvdOU https://t.co/GVuMDAZ8RDObviously @DustinPoirier understands boxing better than @TheNotoriousMMA 😁 twitter.com/mmafighting/st…He also posted a photo on Instagram captioned, "Who’s the best boxer in the UFC? Dustin Poirier says it’s Petr Yan, not Max Holloway." View this post on Instagram Instagram PostThis all came after Poirier appeared on the latest episode of The MMA Hour and shared his thoughts regarding the on-going debate in the MMA community. He said:"I think Petr Yan. I really do. Just the way he moves, the way he doesn't waste a lot of movements. His positioning in always crisp. His footwork, he's never out of position. He doesn't load up but he throws clean power shots. You know, good accuracy, works the body well. Goes up, goes down. It's just a lot of things that he does really, really well."Poirier also acknowledged that he's in the conversation for the debate. However, 'The Diamond' said he's not one to talk highly about himself.Petr Yan and Conor McGregor went back-and-forth on social mediaThe ongoing social media feud between Conor McGregor and Petr Yan stemmed from comments made by the Irishman last week. Claiming to be the best boxer in the UFC, McGregor said he'd "rip up" Yan.Petr “No Mercy” Yan@PetrYanUFCConor, we all know that you like to talk, but let’s get straight to the point if you really want to box or to fight, I don’t care about the weight or the ruleset. I bet you won’t show up @TheNotoriousMMA twitter.com/thenotoriousmm…Conor McGregor@TheNotoriousMMAI outboxed 3 guys on this list! There’s no one even remotely close to my boxing in the ufc. Even Dustin only got shots off post the leg damage. Everyone has been pucked around by me if we are going off boxing. Yan is good tho, i like his style. I’d rip him up in that shell tho. twitter.com/ezrawpodcast/s…5:20 AM · Nov 12, 2021142691083I outboxed 3 guys on this list! There’s no one even remotely close to my boxing in the ufc. Even Dustin only got shots off post the leg damage. Everyone has been pucked around by me if we are going off boxing. Yan is good tho, i like his style. I’d rip him up in that shell tho. twitter.com/ezrawpodcast/s…Conor, we all know that you like to talk, but let’s get straight to the point if you really want to box or to fight, I don’t care about the weight or the ruleset. I bet you won’t show up @TheNotoriousMMA twitter.com/thenotoriousmm…The Russian responded by issuing an open challenge to McGregor. According to Yan, he's willing to fight McGregor in an MMA or boxing match and at any weight class.Conor McGregor@TheNotoriousMMA@PetrYanUFC Lol, no prob littler. We will set up a spar or something similar in the near future. Will host you and your team in Ireland for one of our shows at Crumlin boxing club. We will figure it out then, kid. God bless ya. @ParimatchGlobal, get this set.6:10 AM · Nov 12, 20215473269@PetrYanUFC Lol, no prob littler. We will set up a spar or something similar in the near future. Will host you and your team in Ireland for one of our shows at Crumlin boxing club. We will figure it out then, kid. God bless ya. @ParimatchGlobal, get this set.Not one to be outdone, McGregor replied to Yan's invite with one of his own. The former champ-champ offered to host Yan and his team in Ireland for a sparring session at Crumlin Boxing Club.