The event, first reported by MMA Fighting in early April, will be the organization's first mid-week card, taking place on a Wednesday to coincide with the massive E3 entertainment expo.
The original main event pairing featured Lawler against Jason "Mayhem" Miller, but was changed due to a pending investigation into Miller's actions during the April 17 post-event brawl on CBS. The Tennessee state athletic commission could suspend Miller for inciting the melee after entering the cage to challenge Jake Shields during a post-fight interview, but a decision on Miller's status has yet to come.
Sobral (35-8) is coming off a Dec. 2009 loss to Gegard Mousasi, a defeat which cost him his Strikeforce light-heavyweight title. He had been scheduled to fight in the DREAM light-heavyweight tournament until it was abruptly canceled yesterday.
Lawler, meanwhile, most recently knocked out Melvin Manhoef in January. He is 19-5 with one no contest.
The Sobral-Lawler fight will be contested at a 195-pound catch weight.
Also scheduled on the card are Bobby Lashley and K.J. Noons, though neither has an opponent named as of yet.