The San Francisco 49ers — down to one healthy quarterback — reportedly will sign Josh Rosen to serve as the backup signal-caller this weekend, according to a report from ESPN on Tuesday night.

Rosen most recently has been part of the Tampa Bay Buccaneers’ practice squad. The 23-year-old entered the league as a first-round draft pick (No. 10 overall) in 2018 out of UCLA, but he bounced from the Arizona Cardinals to the Miami Dolphins in his first two seasons before getting a practice-squad invite to Tampa Bay.

In 20 career games (16 starts), Rosen has completed 54.8 percent of his passes for 2,845 yards, 12 touchdowns and 19 interceptions. His career passer rating is 63.5.

C.J. Beathard had been the 49ers’ lone signal-caller heading into Saturday’s game against Arizona. Fellow quarterbacks Jimmy Garoppolo (high-ankle sprain) and Nick Mullens (elbow) are out with injuries, and the team placed practice squad quarterback Josh Johnson on the Reserve/COVID-19 list this week.

San Francisco (5-9) has lost three in a row and six of seven.