But both are plenty familiar with the rivalry.
Herman was a graduate assistant under Mack Brown with the Longhorns in 1999 and 2000. Riley spent the last two seasons as Oklahoma's offensive coordinator.
"I think when you go into one of the most storied rivalries in college football, if not the most, I think it is important that you recognize that this is a big game for a lot of people in both states," Herman said.
"It's a big game because it's a conference game. It's a big game because of the uniqueness of the Texas State Fair and it being on a neutral site every year -- half the stadium is burnt orange and half the stadium is crimson."
It's the first time since 1947 that this long-standing rivalry has featured new coaches on both sides in the same season. That year, Blair Cherry's Texas squad beat Bud Wilkinson's Sooners 34-14.
For both Riley and Herman, the game could be an early reputation-making game.
Struggles in the series have helped lead to coaches on both sides being shown the door, while successes can lead to a longer grace period.
"Responsible is probably the word that comes to my mind," Herman said when asked about how this rivalry can affect a coach's legacy.
"Leading this program is definitely a responsibility unto itself. But I would be naive not to tell you that this rivalry is important to a lot of people -- a lot of stakeholders in this program, a lot of alumni, fans, Texas citizens in the great state of Texas in general. So with that comes a responsibility.
"I think the only time that can be a negative thing is if by recognizing that responsibility it causes you to perform you jobs or your duties differently that you would if you were preparing for any ballgame."
Since their season-opening loss to Maryland, Texas (3-2, 2-0 Big 12) has steadily improved, with its only loss since coming in overtime at USC.
A win over No. 12 Oklahoma (4-1, 1-1) would be a signature victory in Herman's first season -- a year after his Houston Cougars started the season with a signature win over Oklahoma.
Oklahoma climbed as high as No. 2 in the rankings after beating Ohio State on the road Sept. 9, but has struggled in three games since, winning the first two before last week's 38-31 loss to Iowa State.
The Sooners haven't lost back-to-back regular-season games since 1999 -- Bob Stoops' first season in Norman.
The second loss of that stretch came against the Longhorns.
Riley is trying to avoid a repeat of that stretch.
"I think in the past after a tough loss -- we haven't had many around here -- but when we've had them, we've been able to respond regardless of who we've played," Riley said. "I would hope that we have enough pride -- and I feel we do have enough pride as a team -- that we'd be motivated to go play Norman Junior High this week."
That 1999 game was Herman's first Red River game, although the second sticks with him more.
In 2000, Oklahoma whipped Texas 63-14.
"I still remember that score," Herman said. "It's embedded into my brain."
Riley was always aware of the rivalry, growing up in West Texas as the son of two Texas alums.
But he didn't get his first up-close experience with the Cotton Bowl tradition until 2015, when Riley's offense sputtered and unranked Texas upset No. 10 Oklahoma 24-17.
"It was a learning experience for me," Riley said of his first game against the Longhorns.
"It's a different game. It's a different atmosphere. It's closer to a bowl game to me than anything else. I think you've gotta have the kids in the right mind-frame for it, the right mindset, and you've got to be there as a coach and know regardless of what you've seen on tape from either team it's gonna be probably the best and hardest that both those teams have played all year.
"I'd have enjoyed it a lot more if we'd won, but it was a good learning experience. I sort of felt more prepared going into last year."