A scenario that became increasingly likely over the past couple of weeks was made all but official Wednesday. Seahawks Pro Bowl safety Kam Chancellor still has not reported, which means Dion Bailey will start the season opener in St. Louis in his place.

"He's not here right now, so he's not playing," Seahawks coach Pete Carroll said when asked about Chancellor. "That's it.

"I am disappointed in this, very much so. I think everybody should be, because he has been a great part of our team. It's unfortunate that it has come to this and he's not here."

But as disappointing as Chancellor's absence may be, it also represents a great opportunity for Dion Bailey, the young safety out of USC who will start in Chancellor's place. Bailey, who went undrafted in 2014, then spent part of last season on the practice squad, has always believed in his ability to play in the NFL, but even he admits he wasn't expecting to be a Week 1 starter this season.

"It's just a surreal moment," Bailey said. "I never expected to be in this position at this point in my career after the path I've taken. I've got to take advantage of it. I've been waiting my whole life for this opportunity, so the last thing I'll allow is for me not to be mentally prepared."

The path Bailey speaks of includes redshirting as a freshman at USC, then being asked to move from safety to linebacker before eventually moving back to safety. He left USC early expecting to be drafted, then watched the 2014 draft in disbelief as other safeties whom he didn't think were as good as him had their names called.

"My whole football career, the odds have been stacked against me," Bailey said. "People didn't think I was as athletic as the next person or able to do something the next person can do, which is why in college my position was switched from safety to linebacker."

But, Bailey adds, "There's always a positive in every negative situation." For Bailey, the first positive was getting signed by Seattle after the draft, but then came another negative, an ankle injury that kept him from having any chance to win a roster spot in camp as a rookie. Still, Bailey did enough on the practice squad to get a chance to compete in camp this year, and eventually he moved into the starting role heading into the season opener.

Carroll said the Seahawks don't need to change much, if anything, with Bailey replacing Chancellor. Carroll refers to Bailey as a "very natural football player" and an "all-out hitter," and he has the utmost confidence in a player he once recruited out of Lakewood High School in Southern California.

"Dion Bailey has had a great offseason and camp for us," Carroll said. "He's been in that position for quite a while with us. We feel very comfortable that he understands the principles and the fits and all the things he has to do. He's a playmaker and he's a very aggressive tackler, so we're going to count on him to do the things he does well, and hopefully fit him in with this group. We're moving, we're ready to go. We've had a long time getting ready with him, so we feel comfortable with that."

Even though Bailey's NFL debut will come as a starter who is being asked to replace one of the NFL's best safeties, he says the only thing he's feeling right now is excitement, not nerves. The huge grin that kept showing up on Bailey's face indicated he was telling the truth.

"For the first time in my life going into a big game, I don't feel any pressure," he said. "I'm not here to fill Kam's shoes, I'm here to be the best Dion Bailey I can, and the best Dion Bailey has done me well so far for the first 23 years of my life, so I like my chances on Sunday.

"I'm just really excited, all these reporters in my face. I never expected to be in this position, it's really a dream come true. I can't promise you I'm going to go out there and have 100 tackles, but I can promise I won't let this opportunity slip."

Bailey is the first to admit he isn't Kam Chancellor. At 6-foot, 211 pounds, he's not nearly as big as the player he is replacing, nor does he have the experience or impressive résumé. But what Bailey does believe is that he is more than capable of helping the Seahawks have a strong defensive showing in St. Louis this weekend.

"It's going to be a different type of physical presence than Kam—I'm not 6-4, 240—so I hope people aren't expecting me to go out there and be crushing bones and things like that," Bailey said. "But I'm going to do what they're asking me to do to the best of my ability, flying around and making plays."

And if the Rams see an unproven young player filling in for Chancellor and decide that their best plan on offense is to test Bailey, that's a challenge he'll welcome with open arms.

"I hope they plan to come at me," he said. "It'll make my coming out party a lot more exciting. The more opportunities to make plays, the more plays I'll make."