Hall of Fame promoter Don King, who represents Vanes Martirosyan (36-3-1, 21 KOs), cautions that IBF, IBO, WBC, WBA middleweight champion Gennady Golovkin (37-0-1, 33 KOs) is in for a real fight.
Vanes moving up from junior middleweight and coming in on late notice to accept the fight with Golovkin.
Vanes is also fighting for the first time since losing to Erislandy Lara in their 2016 rematch.
Vanes replaced original opponent Saul "Canelo" Alvarez, who on Wednesday was suspended for six months for testing positive for banned substance clenbuterol.
The winner of Golovkin vs. Vanes will be in line for a showdown with Canelo in the fall.
Vanes was ordered to take part in a WBC junior middleweight final eliminator, but the contest never got off the ground because numerous opponents turned him down to fight.
Many experts view Vanes as a huge underdog and give him no chance to upset the odds.
King believes the opposite. He expects Vanes to take the fight to Golovkin in the early rounds to set the tempo for a grueling fireworks filled contest.
"It is going to be a great fight - it is going to be a battle of wills," said King.
"GGG is a great fighter -- he has four belts -- and is supposed to be the best there is. But Vanes has heart, a strong will, and the desire of an Armenian with a never say die attitude, and he is coming to fight. The ticket to this event is going to be hot. This is a hot fight and it's provocative.
"You're not going to be able to go the restroom and you better get your popcorn and sit right there to watch it. It's going to be a super fight and I am looking forward to it. Vanes' desire and the will to win -- that's what creates a hell of a fight, because you don't know what's going to happen."