What's the story?War of words between two of the greatest superstars of the combat sports 2017's hottest sporting rivalries resumed when boxing champion Floyd 'Money' Mayweather tweeted about Conor McGregor earlier this week. Mayweather tweeted a picture that had been taken from a news report which stated that McGregor has a bounty on his head after punching an Irish cartel member.I already fucked you up in 2017 now they about to fuck you up in 2018. You’re about to start your new year off with a bang ?????? pic.twitter.com/upaRfLbgvJ— Floyd Mayweather (@FloydMayweather) January 10, 2018This is after Mayweather had defeated McGregor when they faced off last year at the T-Mobile Arena in Nevada, USA. The Notorious One, however, did not hold back. His reply to Mayweather's tweet was a very witty one.I am the cartel.— Conor McGregor (@TheNotoriousMMA) January 10, 2018In case you didn't know...Mayweather's professional record extended to 50-0 after he knocked out McGregor last summer. The 40-year-old is still undefeated in the boxing ring with 27 knockouts to his name.The heart of the matterThe two haven't stopped here and continued the online war of words on Instagram. Both Mayweather and McGregor shared images from last year's fight with captions trying to take shots at the other person. Violate these nuts ? A post shared by Conor McGregor Official (@thenotoriousmma) on Jan 10, 2018 at 4:34pm PST You violate and I will demonstrate!! A post shared by Floyd Mayweather (@floydmayweather) on Jan 10, 2018 at 4:26pm PSTMayweather ended the war with a picture of him punching Conor with a brutal uppercut, captioning the image, "Please, can somebody give me a caption"? Please, can somebody give me a caption? #MayweatherPromotions #TheMoneyTeam A post shared by Floyd Mayweather (@floydmayweather) on Jan 10, 2018 at 4:38pm PSTWhat's next?Both McGregor and Mayweather have been quiet since last summer's mega bout and neither of them has taken the ring ever since. There has been speculation that a rematch is on the cards with the exception that it will be held in an octagon with MMA rules and not in a boxing ring.Author's takeBoth Mayweather and McGregor have huge egos. Any war of words between them is only going to make the possible rematch more likely and interesting. While it is up to Dana White to arrange the rematch, the fans can enjoy in the meantime as they bash each other on social media.