Cardinals cornerback Brandon Williams will be a starter in his first NFL game on Sunday against the Patriots.

The camera lights flicked on and the media contingent steamrolled toward Brandon Williams in the Cardinals locker room.

The rookie third-round pick couldn't even get his pads off before the bombardment of questions began. The throng wanted to know how a guy with just 15 months of cornerback experience planned to handle his NFL debut, especially under the bright lights of "Sunday Night Football."

"You've got to invite the challenge," said Williams, who was officially named the opening night starter by coach Bruce Arians on Wednesday. "Of course I know I'm going to be picked on. I'm opposite of a Pro Bowl cornerback (Patrick Peterson), arguably the best cornerback in the game right now. I know I'm going to get those eight or nine targets, or whatever. The mindset's got to be, 'I've just got to make more than I give up.' "

Williams isn't fretting. This is far from the first trial in his life.

He was a star running back during his prep days in Brookshire, Texas, but unlike others who could simply enjoy the recruiting process, Williams had more than just himself to worry about. His oldest daughter, Serenity, was born when Williams was still in high school.

"I was scared, obviously," Williams said. "It was very different, very unique. It made me grow up a lot. I was already a hard worker and I already had that drive, but it added that much more to it. I wasn't doing it for myself. I was doing it for my baby girl."

Williams was a five-star recruit and chose to attend Oklahoma over multiple other suitors. His goals weren't different than other freshmen heading to the college ranks, but his freaky speed and athleticism made them seem reachable.

"Every college (player) dreams of being that superstar," Williams said. "Win awards, the Heisman, all that good stuff. Be the next big thing, and that was my expectation."

He had a nice freshman season at Oklahoma, averaging nearly five yards per carry in limited work, but the distance from Serenity was too much to bear. Williams said he had a clear path up the Sooners' depth chart, but he traded it for a chance to be closer to home.

"My whole thing was always being in my child's life, no matter what," Williams said. "I didn't have a dad to support me or help me when I grew up. I wanted to be that great example for my daughters -- that I would always be there for them."

Williams speaks in plural because he had his second child, Lila, after transferring to Texas A&M.

While family life was better in College Station, Williams never became a star tailback. He averaged 29 rushing yards per game over the next two seasons, and his childhood dream of becoming the next Adrian Peterson was vanquished when the Aggies asked him to switch to defense as a senior.

A position change that late is usually a sign of desperation by a coaching staff, but it worked out beautifully for both parties.

Williams' athleticism translated better to cornerback, which helped beef up the Texas A&M secondary. He showed enough on tape to make a believer of the Cardinals, who scooped him up with their second pick in the draft.

It was an improbable turn of events, but Williams never stopped believing he would make the NFL.

"I have a lot of confidence in myself, in how I prepare and what I do," Williams said. "I knew some way, somehow, I was going to be here."

After Williams arrived in Arizona, he immediately latched on to Patrick Peterson. The pair worked out together in the blazing Phoenix heat when the team separated for the summer, and once training camp began, the protégé never left the mentor's side.

"You can tell he wants to be great, because he's always been willing to put the work in," Peterson said. "He's always in my ear about how to get better. Even in the meeting room he's sitting right next to me."

Williams' path to the NFL was unlikely, and so, too, was the idea of him starting as a rookie. But a foot injury kept projected starter Justin Bethel sidelined for much of the offseason, and it left an opening which Williams seized.

He started with the first-team defense from the outset of training camp and never relinquished the position. The cornerback spot opposite Peterson is arguably the biggest question mark on the team, and Arians was asked this week if Williams was ready to fill it.

"He's the best we've got, so he better be," Arians said.

Two-year-old Lila will be at the game on Sunday when Dad makes his debut, but she's too young to comprehend the gravity of it. While Serenity is a half-decade older, she's not football-crazed.

"She knows I change colors and she knows the mascot," Williams said. "That's all she knows. And she knows I'm not living in Texas anymore."

Williams loves that football fades to the background when he spends with time with his children. His Instagram page has several shots of the trio making funny faces at the camera, with no hint of his famous profession in the background.

But it's their presence, and the idea that he can give them a wonderful life if he succeeds, that makes Williams work so hard when it's time to clock in.

"I can honestly say I don't know if I'd be here right now if it wasn't for my daughters," Williams said. "I went through all the hard times getting to here, and my motivation to push through is my daughters."