Shocking video shows Caleb Plant HITTING Jermall Charlo in backstage incident

Caleb Plant HIT Jermall Charlo in a shocking backstage altercation at the Errol Spence vs. Terence Crawford weigh-ins.

The undisputed welterweight showdown between Spence and Crawford goes down tonight in Las Vegas.

Spence and Crawford weighed in on Friday as they both hit the championship mark, tipping the scales at 147lbs and 146.8lbs respectively.

During the weigh-ins, there was an explosive incident which saw former IBF super-middleweight title holder Plant smack Charlo.

A video shows Plant slapping Charlo, sparking a brawl between both sets of entourages.

'Sweethands' was then ushered out of the building by security, with Charlo seen speaking to a member of security before the clip ends.

After weighing in, Spence took to social media to share his thoughts on Plant punching Charlo.

"Caleb & Jermall promoting the #SpenceCrawford fight tomorrow in their own way," he tweeted.

UFC superstar Conor McGregor also reacted to the video of Plant hitting Charlo as he questioned both sides.

On Twitter, he wrote: "Get back here this second Sir, you're going nowhere till we settle this dispute here and now. Wtf is going on there? Clean cracked and let's him walk out? No. nope. Not a f**kin' hope."

A fight between Plant and Charlo had been mooted. Plant hasn't fought since his devastating knockout victory over Anthony Dirrell last October.

As for Charlo, he was linked with a showdown against Canelo Alvarez, who eventually opted to take on his twin brother, Jermell.

The real action, meanwhile, gets underway tonight as WBA (super), WBC and IBF champion Spence meets WBO kingpin Crawford for all the marbles.