ATLANTA — Robert Nkemdiche is just about everybody's number one prospect on national signing day.

Rivals.com, Scout.com, ESPN, CBS Sports and 247Sports all give No. 1 rankings to Nkemdiche, the big defensive end from Grayson High School near Atlanta.

That's good news for Mississippi. Nkemdiche (kem-DEE-CHEE) is expected to sign with the Rebels early Wednesday morning.

Louisiana State and Florida are believed to be Nkemdiche's other finalists. Nkemdiche's last visit was to LSU last weekend. The big edge for Ole Miss is Denzel Nkemdiche, Robert's older brother who led the Rebels in tackles as a redshirt freshman linebacker last season.

The family connection may be an insurmountable advantage, but the late decision to visit LSU added drama to Wednesday's announcement. Nkemdiche's updates on his final visit provided encouragement to LSU fans.

"LSU pushing man!!!! Getting hard now," Nkemdiche tweeted.

In another tweet, he said "LSU pulling out da facts!!!"

Nkemdiche made a public commitment to Clemson last year but then changed his mind, de-committing in November as Ole Miss again moved to the front of his list.

Grayson coach Mickey Conn said that Nkemdiche has been under tremendous pressure and has "clammed up pretty good" about his plans.

"I think it's been extremely tough on him," Conn said. "He's getting pulled in more directions than what most people want. People dream of having this opportunity, but the one thing that gets left out of this is the pressure. The stress of making the right choice is something a lot of people don't understand, and then you involve the family aspect. Having a brother who is playing at Ole Miss adds more pressure to Robert.

"He wants to make the right choice."

Though there is pressure, Conn said Nkemdiche (6-4, 280) has embraced the process.

"He's been taking visits since he was in the ninth grade," Conn said. "He's been to all the big schools, maybe not on official visits, but Robert has not been shorted on being treated to the red carpet at all these places. He's well aware of what's out there."

Nkemdiche's combination of size and explosive quickness prompted veteran recruiting analyst Tom Lemming of CBS Sports to draw comparisons with past and current stars.

"He's built more like Reggie White and he has an explosive first step like Jadeveon Clowney," Lemming said. White is a Hall of Famer regarded as one of the best defensive linemen in NFL history. Clowney placed sixth in the Heisman Trophy voting as a sophomore at South Carolina last season.

"I've been doing this 34 years," Lemming said. "My second year, Reggie White came out of Howard High School in Chattanooga. He kind of has a Reggie White type build. Similar. I'm not saying he's as good as that until he gets there. He has that same great first step and quickness and body control and almost similar build, so he's got what it takes to make it big on the next level.

"The only thing we can't determine yet is his work ethic once he gets to college."

Lemming said Nkemdiche explodes off the line like Clowney.

"They both have that great first step," Lemming said. "I don't think he's as good as Clowney, but he's not that far off. I think he's got all the tools."

Nkemdiche had 18 sacks as a junior to lead Grayson to the 2011 Class AAAAA state championship. He had only five sacks as a senior, thanks to extra attention from offensive lines.

"He's a guy who demands the double-team," Lemming said. "With two or three guys on him this year he still played well."

Lemming said he believes it is a "just a forgone conclusion" that Nkemdiche will join his brother at Ole Miss. Denzel has openly lobbied for his brother to sign with the Rebels.

"I told him 'We need you, you know how I feel about that,'" Denzel said.