QuarterbackThe battle: Alex Smith vs. Colin Kaepernick
The skinny: Though by all appearances Smith will enter the regular season as San Francisco's starting quarterback for the fourth time since he was selected by the team with the No. 1 overall pick of the 2005 NFL draft, coach Jim Harbaugh still has not announced that decision yet. Since both quarterbacks have struggled mightily during the preseason – weak pass protection has played a big factor in that – there is a slim possibility the light could go on tonight for Kaepernick and he could be impressive enough to persuade Harbaugh to make a radical decision to go with the rookie and be damned at the start of the season. That seems highly unlikely, but it is not out of the realm of possibility, particularly since Smith has done nothing during the preseason to suggest that he will be successful in yet another chance at the job that was given to him without a fight at this time last year.
The leader entering Thursday's game: Smith
Right cornerbackThe battle: Tarell Brown vs. Tramaine Brock
The skinny: With Shawntae Spencer missing most of the summer and all of the preseason with a recurring hamstring problem, the 49ers must get someone else ready to open the regular season opposite left cornerback Carlos Rogers in the team's revamped secondary. Spencer said on Wednesday that he expects to be ready for the season opener, but the 49ers can't expect the veteran to just show up as the starter without any summer work. So that makes tonight's game all the more important for Brown and Brock, one of which will likely be expected to step in as the starter on Sept. 11. These two players also are competing for a regular role among San Francisco's top three cornerbacks once Spencer actually does return to full strength. Brock had a solid training camp and started the first two preseason games, but Brown – who missed time in training camp with an injury – overtook him as the starter last week and is the more skilled and experienced player.
The leader entering Thursday's game: Brown
Split endThe battle: Braylon Edwards vs. Ted Ginn Jr.
The skinny: The 49ers can't expect Michael Crabtree to be much of a factor in the season opener after spending most of the summer on the physically unable to perform list, so they need to get one of these veterans ready as the starter opposite flanker Josh Morgan. Ginn has remained atop the depth chart here all summer even though he has been outplayed by Edwards during the preseason. There still is some question whether Edwards will have to serve a NFL suspension for off-the-field issues in the opener, so that may be playing into the coaches' thinking here, as they continued to bring along Edwards slowly while keeping Ginn with the first team. Ginn ostensibly is leading the battle in the minds of coaches, but if Edwards is cleared to play in the opener, he could overtake Ginn by the start of the season. In any case, Edwards promises to have a bigger role than Ginn in the passing game as the season progresses.
The leader entering Thursday's game: Ginn
CenterThe battle: Jonathan Goodwin vs. Adam Snyder
The skinny: The long-expected move to Goodwin finally happened this week as he got most of the first-team reps during practice and will start against the Chargers after Snyder started the first three preseason games at center. The 49ers gave Snyder a long look at center this summer, keeping him with the first team throughout training camp and the preseason before finally placing Goodwin's name at the top of the depth chart this week. Goodwin hasn't officially been named the starter, however, so there still is a battle going on here, and Snyder has stayed close enough in the competition to still have a shot to get back with the first unit before the season begins.
The leader entering Thursday's game: Goodwin
No. 2 running backThe battle: Kendall Hunter vs. Anthony Dixon
The skinny: Dixon was the clear frontrunner to be Frank Gore's primary backup entering the summer, but he has been outplayed by fourth-round pick Hunter, who has displayed excellent vision and explosiveness while being one of the team's few offensive stars during the preseason. Hunter has performed well in each preseason game and has displayed a dynamic that could earn him a regular role in the offense. Hunter is the NFL's leading rusher during the preseason with 174 yards on 24 carries, a 7.3 average. Dixon, meanwhile, continues to show hesitation instead of straight-ahead burst with the football in his hands. Dixon has rushed for 84 yards on 27 carries in the preseason, a 3.1 average, and may be more trying to hold off Xavier Omon on the depth chart than he is battling with Hunter. Dixon, however, remained No. 2 on the depth chart released by the team earlier this week, and his experience does count for something.
The leader entering Thursday's game: Hunter
FullbackThe battle: Moran Norris vs. Bruce Miller
The skinny: Miller, the team's seventh-round draft pick, has made a promising conversion to the offensive side of the football this summer after being a star defensive end in college. He appears to have more mobility and versatility than Norris and clearly outplayed the veteran in the second exhibition game against Oakland, the only preseason outing so far where San Francisco's offensive unit had some consistent success. Whether Miller has passed Norris as the pounding lead blocker the 49ers would like to have in front of Gore and the team's other halfbacks remains to be seen. The 49ers may decide to keep two fullbacks on their final roster, and if that's the case, these two probably will be used uniformly as situational players. If the team decides to keep just one fullback, this battle is still too close to call, and it may be decided by what happens tonight.
The leader entering Thursday's game: Even
Outside linebackerThe battle: Parys Haralson vs. Aldon Smith
The skinny: Smith had an outstanding training camp and a solid start to the exhibition season, and he appeared destined to eventually pass Haralson as the starter at right outside linebacker before the regular season began. But Smith has tailed off a bit in recent weeks, perhaps hitting some sort of developmental wall, and his play last week against Houston suggests he still has plenty to learn in pass coverage. Haralson, meanwhile, has been steady after a slow summer start and may be the safer bet as the starter entering the season. Smith could still flash enough against the Chargers for the 49ers to consider moving him ahead of Haralson – who has been No. 1 on the depth chart here all summer – but it's more likely the team will work Smith into the lineup gradually while giving both players prominent roles in the OLB rotation.
The leader entering Thursday's game: Haralson.