LAS VEGAS – Fighters can be kind, compassionate human beings outside the ring. Knowing the bell that tolls to start the first round is arriving, however, can flip a switch.

Seeing unbeaten junior-middleweight Vergil Ortiz Jr. stray from his usual personality this fight week as he inches closer to Saturday night’s Mandalay Bay main event against World Boxing Council interim champion and former sparring partner Serhii Bohachuk is likely a reflection of that.

On Friday’s ProBox TV “Top Stories,” former 140-pound champion Chris Algieri said he relates to Ortiz shifting from his good-guy reputation by refusing to shake Bohachuk’s extended hand at Thursday’s news conference, and then watching his father lash out at Team Bohachuk at Friday’s ceremonial weigh-in.

“I can see Vergil saying, ‘I’ve got to draw a line in the sand,’” Algieri said. “That was sparring. This is fight night. He’s putting himself into that dark space fighters need to get into – especially Vergil: ‘I like to fight, I like to hurt people.’ You need to put yourself into a certain space to tap into that energy.

“It’s so foreign to see Vergil act that way. It’s another caveat that makes this fight so interesting.”

Just 26, Texas’ Ortiz (21-0, 21 KOs) is seen as a future champion capable of eventually standing as the best of a deep division that counts unbeaten four-division champion Terence Crawford and WBC/World Boxing Organization belt-wearing Sebastian Fundora as champions, along with former champion Tim Tszyu as a top contender.

Ortiz promoter Oscar De La Hoya admitted he’s already had a chat with Saudi Arabia power broker Turki Alalshikh about making an International Boxing Federation title fight against Tszyu should Tszyu defeat new champion Bakhram Murtazaliev in the fall.

But first, Ortiz has to pass the test of Saturday night.

After dealing with health issues that prevented him from fighting current welterweight champion Eimantas Stanionis, Ortiz has cruised through two first-round knockouts this year. The outcomes were fun to watch, but is that two rounds of live action in two years enough work to be prepared for Ukraine’s Bohachuk (24-1, 23 KOs), who’s piled up 21 rounds in four bouts during that same window?

“Vergil’s always had a lot of pressure because he’s so talented,” Algieri said. “He’s been looking for a big fight for so years. There’s been this pause or stutter. He seems talented enough to deal with (the pressure), but you can deal with it until you can’t.

“To look past Bohachuk is a dangerous thing.”

We’ve seen recent episodes where losing sight on the task at hand has been costly. Just last week, Mexico’s Isaac “Pitbull” Cruz likely blew his chance for a rematch with World Boxing Association champion Gervonta “Tank” Davis by losing his WBA 140-pound belt by decision to Jose “Rayo” Valenzuela.

Earlier this year, veteran heavyweight Deontay Wilder lost his shot at Anthony Joshua by getting knocked out by China’s Zhilei Zhang.

“It’s one foot in front of the other,” Algieri said. “They believe Vergil can shoulder this. Oscar is excited about Vergil. We’ll see if it pans out.”

Fellow ProBox TV analyst Paulie Malignaggi said he’d rather have the expectations attached to Ortiz’s 100 percent knockout ratio and being a fighter no one talks about.

“Now, you get to the point where there’s risk here,” Malignaggi said. “For both guys. Can you live up to the hype or not?

“Bohachuk grinds you down … he buries you in activity, then stops you. Who can back the other guy up? That’s the key.”

Bohachuk’s punching power and proven ability to last 12 rounds – Ortiz has only reached the ninth round once thanks to his KO propensity – “shows his class and strength.

“When you add up the details, this is a tough fight and Bohachuk is a very live dog,” Algieri said. “It’s a true test, and the winner is a major player at 154 (pounds).”