It'll mark the end of what has been a short stay of games in the home crimson uniform throughout his senior year.
It'll stand as the last time he ever walks out in between the lines as a college football player on his own field, one that he has called that for a single season after playing for three at Penn State.
But the 6-foot-3, 209-pound wide out won't be thinking about any of that when he jaunts out in front of 85,000-plus raucous fans.
In fact, he hasn't even pondered what the moment will be like when his parents--his mother has been to a couple of games this year and his father one---get to be right there with him.
"I'm not sure," Brown said. "I'll just have to tap into those if they come. You know, I'm not gonna be anticipating it or thinking about it too much. I'm just gonna try to focus on the game and what I can do. I'm not gonna be trying to compare and thinking about other things that are not gonna help us win the game."
By trying to compare, he of course means he won't be lining up how it would be to walk out at Happy Valley for his final collegiate contest with respect to the feeling of doing so at Oklahoma Memorial Stadium which has become a reality after the tragic events that transpired at Penn State a year ago.
The reality is that's how Brown has operated since making the transfer during fall camp.
The past has truly been the past for him for the entire four months, and that's allowed him to truck on.
"He's been really good, and I think he has to," said co-offensive coordinator and receivers coach Jay Norvell. "He has to think that way to be able to focus on the moment because he's a very loyal person and he's had to put that behind him. I think it was hard. At the very beginning I think it was hard for him to put Penn State out of his mind, but he had to turn the page and move forward. And ever since he's done that, he's never looked back."
In doing so, he's put together the most productive year of his career, already recording 12 more catches than any other season in his four years with his current mark of 47.
Four of those have been touchdowns, twice as much as any other season in his career, and he's racked up 649 total yards and 13.8 yards per catch.
Not only that, but Brown has also stabilized the punt return game, where he has a 90-yard touchdown amongst his 19 returns for 308 yards.
On top of all the numbers, he's proved to be one of the most studious players at OU in a while.
I have to say this: He's one of the best guys preparing to play that I've ever been around," Norvell said. "I mean he's a meticulous note taker. I'm gonna give his notebook to Trey Metoyer when he leaves because he takes meticulous notes about every defense and every guy that he's played against. And that's [who], the guys that work the hardest and prepare the hardest, they improve faster, and Justin has certainly done that and that's a real credit to him."
Ask head coach Bob Stoops, though, and he'll tell you that's exactly what he expected out of the veteran.
"Yeah, he's been--he's made a great contribution in many ways," Stoops said. "You know, his leadership, his attitude, his how businesslike he is in how he works. But then the big plays he's made. You know, he's been a consistent competitor, catching the ball, punt returns, making big plays, blocking. He's been great."
And the thing is, in doing all that, he's a selfless guy.
"I really don't wanna be remembered like individually," Brown said. "I just want our team to get a lot of recognition. You know, I think we've had a pretty good year so far, but we gotta finish strong. I just want the season to speak for itself, and I hope the season speaks for the players individually, too."
That gets at exactly what Norvell speaks of when his senior is brought up.
Yes, Brown came to Oklahoma as much because it was a good opportunity and fit for him than anything else.
But he wanted to take home something he never got to while donning the blue and white.
"He's still not done, you know," Norvell said. "and he wanted to help us win a championship. I mean that was a big part of it, and he still has an opportunity to help us do that. That door's not closed, and he's trying to do everything he can to help us in every way win a championship."
National championship, out of the picture.
But the Big 12 Championship is possibly right there for the taking.
Never mind all that, however, because on this day it'll be about going out right in a home uni for the final time.
"You know, just going and taking the field with basically my new teammates," Brown said when thinking about Senior Day. "You know, my new friendships I started down here and I'm gonna continue to have after I leave here. That's what it's gonna mean to me."
He's certainly meant a lot to the Sooners, even if it's been for just one year, and even if he came the way of Penn State first.
"I really can't say enough about him," Norvell said. "You know, he's given up so much to come here. And he really had to put his trust in us as coaches. Didn't really know us very well. We got to know him very quickly. But he just believed in Coach Stoops and our offense and playing with Landry [Jones] and being at Oklahoma."
His legacy has been left.