UFC 229 is set to be wild after a dramatic face-off saw Conor McGregor lash out at Khabib Nurmagomedov with a kick as the pair fronted each other for the final time on the eve of Saturday's showdown.

The animosity between McGregor and Khabib has been on display leading into the blockbuster lightweight battle in Las Vegas – a hatred stemming from April's incident in Brooklyn.

McGregor was involved in an attack on a bus at a UFC 223 media day after a reported run-in between Russian lightweight champion Khabib and the Irishman's training partner Artem Lobov – the former later turning himself into police and pleading guilty to disorderly conduct.

The pair's history has dominated the agenda during the build-up and it reared its head again following Friday's weigh-ins.

McGregor – who will make his comeback to the octagon after almost two years away – weighed in at 154.5 pounds after Khabib had tipped the scales right on the 155-lbs limit.

Once the weigh-ins were completed, McGregor stepped out on stage, with popular Canadian rapper Drake draped in an Irish flag.

McGregor then tried to get up close and personal with Khabib, initially slapping down his opponent's lead arm before launching a front kick as the two fighters had to be separated.

A sea of officials swarmed in to prevent McGregor from trying to get to Khabib again, though things eventually cooled down.

Having spent time away from UFC to fight boxer Floyd Mayweather Jr last year, McGregor said: "It's good to be back! UFC fans, it's good to be f****** back! The king is home."

A chorus of boos drowned out Khabib but the unbeaten champion said: "Tomorrow night, I'm going to smash your boy. I'm going to smash your boy, and I want to say thank you all Irish fans, all fans around the world, because of you guys, this fight is happening."