Who will replace Branden Oliver as the No. 3 running back?
The lead candidate, rookie Kenneth Farrow, looked sharp Thursday night.
Against 49ers backups at Qualcomm Stadium, he ripped off a 44-yard run after making an astute, smooth move around left end.
On the next play, Farrow made two decisive cuts that took him into the end zone.
He also caught a Kellen Clemens pass for 16 yards.
Farrow, who had missed the previous two exhibition games, one due to injury, was a three-time captain for the Houston Cougars and rushed for 10 touchdowns last year on a 13-1 team.