Without a title on the line there may be no prospect of a second coronation on Saturday night, but Ireland’s Conor McGregor is still treated like a king in Las Vegas – for the time being at least.

The 27-year-old appeared at an open training session at a packed Jaberwockeez Theatre at the MGM Grand in Las Vegas on Wednesday afternoon looking trim, toned and ready to face Nate Diaz on Saturday.

The theatrical venue couldn’t have been more fitting. Part super-hero, part pantomime villain, McGregor inspires devotion and revulsion, but if the training session in front of fans is anything to go by, the measure of each is far from equal.

McGregor, the featherweight world champion, had been hoping to become the first man to hold two UFC belts at the same time, but an injury to reigning lightweight champion Rafael dos Anjos put an end to that possibility for the foreseeable future.

Knowing that no McGregor on the card would have a huge impact on ticket and pay-per-view sales, the UFC moved quickly to ask Diaz to step into the breach.

Several hundred queued patiently before they were allowed in to the open workout, and the vast majority were there to catch a glimpse of the Irishman with the fast moves and even faster mouth who has made a rapid ascent to the top of the sport.

Packed like sardines into the venue, it wasn’t long before the first chorus of “Olé Olé Olé” began from the small but vocal coterie of Irish fans, who came from Derry and Boston and New York to cheer him on.

Their choruses turned to boos as the announcer revealed that the first of the four fighters out on stage would be Diaz.

One fan roared “You suck!” as Diaz took the stage, ensuring that the first part of Diaz to get a work-out was his middle finger, which he defiantly held aloft in the fan’s direction.

Diaz did the best he could in the open training session, which has to be one of the strangest rituals in modern sport – shadow-boxing with his trainer, rolling around on the mat and snapping kicks that stopped well short of their target for all of five minutes before facing the media.

The workout is as much for the ego as it is for the muscles, and Diaz, tired of playing second fiddle to McGregor, talked up his stature.

“I’m a big fight too. It’s not one-sided,” the 30-year-old told reporters. “If you’re gonna fight anybody, it’s me.”

What little atmosphere there was during Diaz's workout died down as women's bantamweight world champion Holly Holm and her opponent Miesha Taite went through the motions.

McGregor then kept the fans waiting for nearly an hour before making his regal entrance. It didn’t matter. The whole place erupted.

Unlike the others, he broke a sweat too, going through the full range of strikes and kicks and feline movement before engaging in a bout of verbal sparring with the journalists, and aiming a few barbs at those opponents who don’t bother to show up.

“I’m the 145-pound champion, I tried to get that 155-pound belt but he went running,” he said, adding that the fact that he was going up two weight classes meant he was enjoying being able to eat with impunity.

“I go and do a completely different body type, completely different style, different weight – that’s what champions are. And I won’t stop here. I’ll keep going.”

The UFC tends to inspire devotion in its base of hardcore fans, but even that goes up a notch when McGregor is involved. A French visual artist spent the afternoon walking around clutching a clay bust he made of McGregor in his famous roaring pose, hoping for the chance to present it to him.

The open training session may have seen no punches thrown in anger, and even the verbal combativeness for which McGregor is known was somewhat subdued.

But that will all change on Thursday when the first real jousting starts as the fighters appear at a joint press conference ahead of Saturday’s fight.

McGregor may be king for now and even though it is unlikely that Diaz could dethrone him completely with a win, the American will be at least looking to knock the Irishman’s crown askew on Saturday.

Not many in Vegas are betting that he can do it.