You know a team has high expectations when more than half of its starters emerge from the locker room at the start of the exhibition finale without their helmets.
The 49ers who sat out Thursday against San Diego included the entire starting defense, running back Frank Gore and receivers Randy Moss, Michael Crabtree and Kyle Williams.
Quarterback Alex Smith and the starting offensive line began the game. But Smith left after five plays, all of them handoffs that assured that Smith, who absorbed some wicked hits in the first three preseason games, would remain untouched in this one.
From there, Colin Kaepernick took over the 11-play opening drive, which ended with Anthony Dixon plunging into the end zone from one yard out. The 49ers ran the ball nine times on the opening drive.
For the last decade or so, the 49ers were a rebuilding team that needed to give their starters a lot of snaps in the fourth preseason game. Their usual fourth-game opponent, San Diego, typically would sit quarterback Philip Rivers and their starters.
This time it was Rivers and the Chargers starters going against the 49ers' backups during the first quarter. And the 49ers reserves had the upper hand. On the Chargers' first drive, safety C.J. Spillman stripped tight end Antonio Gates of the ball, which was picked up by fellow safety Trenton Robinson and returned 22 yards.
On the Chargers' ensuing drive, Rivers was intercepted at the goal line by another backup safety Darcel McBath. With Smith on the sideline, the focus Thursday was on the 49ers' backups.
After Robinson's fumble recovery, Kaepernick nearly hit Brett Swain deep on the right sideline. One play later, he ran forward in the pocket, kept his head up and saw that Delanie Walker had gotten behind the linebacker covering him. Kaepernick threw a dart along the left sideline to Walker, who broke through Chargers safety Atari Bigby's tackle and then did a falling tap dance into the end zone.
It was the first touchdown pass for Kaepernick in a 49ers uniform. Kaepernick got touchdown No. 2 in the second quarter when on third down he bought extra time by rolling out to his right before finding rookie A.J. Jenkins by himself in the back of the end zone. The 12-yard touchdown was Jenkins' first as a 49er.
Throughout the first half, Kaepernick showed why the 49ers used a high, second-round draft pick on him: He's excellent at evading defenses with his quick feet and then making them pay with his big arm. Kaepernick went into the half 12-18 for 158 yards and a 131.3 passer rating. Jenkins had three catches for 35 yards.
-- Matt Barrows