The 49ers third-string quarterback will be under center Thursday.San Francisco signal caller C.J. Beathard will not start against the Raiders as he continues to deal with a sprained wrist he suffered in his team’s 18-15 loss to the Cardinals in Week 8, according to a report from ESPN. Related News Buccaneers QB Jameis Winston on being benched: ‘I’m not getting the job done’ Giants should replace Eli Manning, says Terrell Owens Nick Mullens, an undrafted free agent out of Southern Mississippi who has never appeared in a regular-season game, will start in his place.”Nick’s a very smart guy who works at it nonstop,” 49ers coach Kyle Shanahan said earlier this week (via the San Francisco Chronicle). “And he’ll be able to go in there and execute the offense. He knows what he’s doing.” Beathard is still struggling to grip a football, but he will serve as the backup against Oakland.San Francisco’s starting QB tonight against the Oakland Raiders will be Nick Mullens, per source.C.J. Beathard will serve as his backup, but with his wrist injury affecting his grip on the football, Mullens will make his first NFL start and throw his first NFL pass.— Adam Schefter (@AdamSchefter) November 1, 2018Beathard was inserted into the starting lineup after Jimmy Garoppolo tore his ACL in late September. He has completed 60.4 percent of his passes and thrown eight touchdowns, along with seven interceptions, in six games this season.