Just a day after Alex Volkanovski had been announced as the next challenger for the UFC lightweight crown, Conor McGregor launched a stunning attack at the Australian champion through social media.

The stage had been set over the weekend for featherweight king Volkanovski to showdown with Islam Makhachev in a champion vs champion fight next year, but McGregor isn't a fan of the match-up and decided to let the world know.

The Irishman posted a photo of the pair and said the fight wouldn't be popular with fight fans, doing only double-digit pay-per-view buys.

'My two old belts. On two little ticks. This fight does 10 buys,' he tweeted.

The dig at Volkanovski sparked a response from the Aussie, who used McGregor's own words against him in a reply.

'A former wise man once said,' he replied to a previous McGregor tweet, which said 'winners focus on winning. Losers focus winners'.

'Notorious' quickly changed the topic of conversation and said he was happy for the Aussie and that 'this is not over'.

McGregor then offered Volkanovski advice on how he should approach his lightweight debut against Makhachev.

'I was in your exact spot one time don't forget. 145 coming up. Good luck,' he wrote.

'I'd say go heavier. Rugby days. Be a bowling ball. That's how I'd do it as you. Your condition right now as I see it, I don't know. But bowling ball style for you for best chance.'

Volkanovski has long expressed interest in a title bout against McGregor, despite the inactivity of the Irish superstar.

'It's always going to be a big fight, there's always going to be money, there's going to be a circus, it's going to be entertaining, it's going to be fun, I'll enjoy that whole f--king thing,' Volkanovski told TMZ sports.

McGregor is just 1-3 in MMA bouts since 2016 and is coming off back-to-back losses to Dustin Poirier and a serious injury.  

Volkanovski, meanwhile, continues to rise and remains undefeated since joining the UFC and and is currently the No.1 pound-for-pound fighter in the world. 

UFC boss Dana White recently revealed that McGregor must undergo six months of drug tests before he can fight again. According to reports, he is the only UFC fighter yet to be drug tested by USADA this year despite his plans to return to the octagon in the coming months.