And one of them is a complementary back for starter Melvin Gordon.
"Who's stepping up in the backfield to be the tandem back with Melvin (is one of the position battles to watch for)," Lynn said this week.
Branden Oliver has been used as the team's main change-of-pace back with Gordon when the starters have played during preseason play, but it appears the Buffalo product's role of complementary back is written in pencil, not pen.
Bruising runner Andre Williams has the most carries of any running back with 26 in exhibition play, but he's totaled just 52 yards (2.0 per carry) and has fumbled.
Limited during training camp because of injuries, Kenjon Barner has just six carries for minus-1 rushing yard.
Undrafted rookie Austin Ekeler has been the most productive with 37 rushing yards, averaging 5.3 yards per carry.
And Kenneth Farrow remains sidelined with an ankle injury.
Along with what player will emerge as the tandem back, here are five other questions for the Chargers as they face the 49ers:
How does Feeney Look? Looking back at the game against the Los Angeles Rams last week, I was impressed with the way the Chargers' starting offensive line performed in pass protection and the running game. Specifically, I thought right guard Kenny Wiggins played well, even though it was against the Rams' second defense. So I'm interested to see how third-round selection Dan Feeney progresses and if he can develop into a solid, interior depth player for the Chargers during the regular season.
Who's taking the lead at MLB? Lynn said the only starter who will play on Thursday is middle linebacker Korey Toomer, who's in a battle for the starting job with Nick Dzubnar. I asked Lynn if Jatavis Brown was a consideration for middle linebacker because he plays there when the Chargers go with five defensive backs. Lynn said Brown already serves as the defensive play caller and wore the green dot on his helmet last week against the Rams, but for now he wants to leave Brown on the weak side. How Toomer and Dzubnar play against the 49ers will be closely watched by Lynn and the coaching staff.
Who wins the return jobs? Barner is penciled in as the team's starting kick returner and Travis Benjamin as the starting punter returner, but those jobs remain up for grabs. Can someone like Ekeler, Desmond King or Mitchell Paige make some noise against San Francisco with a big return?
Will McCain's impressive play continue? With 1.5 sacks in exhibition play, defensive end Chris McCain leads the Chargers. McCain also has 10 combined tackles and a pass broke up, and overall has been a disruptive force through three games. The Chargers would like to see more of the same from McCain against San Francisco.
Can Jones move the offense? Cardale Jones likely will get his most extensive work of the preseason against the 49ers, potentially getting the start over No. 2 quarterback Kellen Clemens. Jones looked more comfortable running the offense last week against the Rams, but has to figure out a way to get the offense into the end zone a couple times on Thursday.