Mendenhall announced Friday that Nelson will start tonight (8:15 p.m., MT, ESPNU) against San Jose State in place of sophomore Jake Heaps, who has started the last 15 games for the Cougars. Nelson hasn't started a game since BYU faced Florida State on Sept. 18, 2010.
"My decision to start Riley on Saturday is based on the productivity of our offense at the end of last week's victory over Utah State," Mendenhall said in a statement. "After coming out of the game last week, Jake has responded very well with an excellent week of practice and he is eager for his next opportunity. I have confidence that both quarterbacks can lead this team."
While BYU has been unsettled at the quarterback position this week, it is riding a modest two-game winning streak.
The Cougars are looking to build on that momentum.
"We talked a lot about that in our team meeting on Monday. We have to get the flywheel rolling and get on a little roll here," said linebacker Brandon Ogletree. "That's what we feel like, that one win leads to another. As long as we keep building in practice every week, and getting better, kind of like what we saw at the end of last season. We did a really good job of getting better every single week. That's our goal."
"I don't think we've reached our potential as a team yet," said tight end Marcus Mathews. "We're definitely taking the right steps. We're getting there."
The Cougars are coming off their highest scoring game of the season with a 27-24 victory over USU. Led by Nelson, who replaced an ineffective Heaps late in the third quarter, BYU scored two touchdowns in the fourth quarter, including the game-winner with 11 seconds remaining.
The Cougars were just happy to secure a victory, no matter the circumstances. "It feels a lot better to be 3-2," Nelson said, "than 2-3."
Last Friday's win resulted in Cougar coaches re-evaluating the quarterback position this week.
Asked earlier this week if he wanted to be the starter, Nelson replied, "Whatever helps the team win."
On Wednesday, Mendenhall said leadership and productivity would figure heavily in choosing a starting QB.
"It's a pretty complex decision. You need to care for each young man and their future and then also the future of the program at that position. All of those things will be considered. There's no saying that whomever starts this Saturday retains that job. It could be fairly competitive the rest of the year. There's all kinds of different options available."
Ogletree said the team is not distracted by the QB quandary. "Everyone else worries about it, but we don't worry about it. We have faith in the coaches and we know whoever is playing quarterback is going to give it his all."
The Cougars have won three games this season by a total of 11 points, and they could have another stiff challenge on their hands against SJSU.
"They're a solid team," said center Terence Brown. "They beat Colorado State last week. Colorado State beat Utah State and we had a hard time with Utah State. They're going to play hard."
The Spartans, who have won two straight games for the first time in three years, boast one of the leading rushers in the country. Running back Brandon Rutley averages 103 yards per game, although he has been hobbled by an ankle injury. The Cougars have prepared as if Rutley will play.
"They have a really good running back who's capable of going the whole distance at any time," Mendenhall said. "He's really elusive. Then they have a nice ball-control passing attack where they throw it before you can get there and just move the chains methodically."
Spartan quarterback Matt Faulkner has gained a lot of confidence in recent weeks, having thrown for 549 yards and four touchdowns in his last two games.
Nothing has come easy for BYU this season, and it's likely the Cougars will be in for another dogfight Saturday night.
"Like most teams, you hope to turn on the film and think that it is going to be an easy opponent, but after watching San Jose State I don't think that and our defensive staff doesn't think that," Mendenhall said. "They are very skilled and capable."
Cougars on the air
San Jose State (2-3) at BYU (3-2)
Saturday, 8:15 p.m. MT
LaVell Edwards Stadium
Radio: 1160 AM, 102.7 FM