DENVER Alex Smith and Peyton Manning are sure to get plenty of close-ups in today's nationally televised game considering the 49ers' dalliance with Manning in March.
But it's their backups who will get close scrutiny from coaches and evaluators around the NFL.
Jim Harbaugh said this week that Colin Kaepernick was in position to enter the regular season as the team's No. 2 passer. That likely leaves one spot on the final roster for either Josh Johnson or Scott Tolzien.
Perhaps in an effort to spark a trade, Harbaugh and the 49ers have been careful not to tip their hand about which passer they prefer. In fact, the refrain from Harbaugh this offseason is that the 49ers feel they have four starter-quality quarterbacks on the roster.
In the exhibition opener, Tolzien got in the game before Johnson. In the next game, Johnson got the nod over Tolzien. Harbaugh would not say which quarterback will enter the game first today.
Through two games, Tolzien is 14 for 22 for a team-leading 107 yards. He has a 56.4 passer rating that's due largely to the interception he threw against Minnesota in which he was hit by a defender upon his release.
Johnson is 6 for 10 for 94 yards and has a 91.2 rating. He had a chance for two highlight-grabbing throws to wide receiver A.J. Jenkins last week, but just missed him on both attempts.
"I just overthrew him," Johnson said. "For us as quarterbacks, it's about his relationship to the defender. And then it's about putting it out there and letting him go get it and trusting that he's going to make the play for you. And that's what we do out here in practice build that trust with these guys."
Like the other 31 teams, the 49ers must reduce their roster to 75 players by 1 p.m. Monday and then to 53 players by 6 p.m. Friday. That means 36 players will be released.
Other positions also are coming down to the wire.
Running back Brandon Jacobs won't play today and is unlikely to take part in Thursday's preseason finale against San Diego after suffering a knee injury in Houston. Still, Harbaugh said the seven-year veteran did enough over the offseason to earn a spot on the final roster.
That's bad news for Anthony Dixon, who took over short-yardage duties from Jacobs against the Texans. Another running back, Rock Cartwright, likely is safe because of his value on special-teams coverage units.
Meanwhile, Demarcus Dobbs holds the fate of two positions.
The defensive end has played tight end in each of the 49ers' exhibition games. If coaches feel comfortable with him as the No. 3 tight end behind Vernon Davis and Delanie Walker, Konrad Reuland could lose a spot on the 53-man roster. Reuland is eligible for the practice squad.
Dobbs also entered the Texans game early as a situational pass rusher. That means the 49ers, who went into the season with only three outside linebackers last season, could do the same this year.
"Heck, yeah," Harbaugh said when asked if Dobbs could be worked into the regular-season rotation as a third-down pass rusher. "He's coming along real nice."
The team's top three outside linebackers are Aldon Smith, Ahmad Brooks and Parys Haralson. If Dobbs served as the emergency fourth linebacker, it would make Eric Bakhtiari, who leads the 49ers in sacks and tackles through two games, expendable.
Bakhtiari is not eligible to land on the practice squad.