SANTA CLARA, Calif. -- It has been almost exactly a week since the San Francisco 49ers traded for quarterback Jimmy Garoppolo. But as Garoppolo enters his second week with the team, it doesn't sound like the plan for when he will make his Niners debut has changed.

Niners coach Kyle Shanahan, who has maintained since the team acquired Garoppolo that the decision on when to play him will be a week-to-week proposition, said Monday the early plan for this week is for Garoppolo again to serve as the backup to rookie C.J. Beathard and replace him only in the event of an injury.

As part of that plan, the banged-up 49ers will once again eschew signing a third quarterback such as veteran Matt Barkley, who could ensure that Garoppolo won't play until he gets a healthier supporting cast and/or a better grasp of Shanahan's scheme.

Niners coach Kyle Shanahan said Monday the plan is for recently acquired quarterback Jimmy Garoppolo to again serve as the backup to rookie C.J. Beathard on Sunday against the Giants, and only replace him in the event of injury. Kyle Terada/USA TODAY Sports

"We feel Jimmy is about where [an outside quarterback] would be, especially them not being with us for the last few months," Shanahan said. "Also, you'd have to cut other players to do that, and we don't have that leeway right now just to cut a lot of other guys. Everybody is playing a role on our team right now with the injuries we have now. If you can't IR guys, you don't lose that spot, so we really don't have the room for that right now."

In Sunday's 20-10 loss to the Arizona Cardinals, Garoppolo was active and was the backup to Beathard. Although Garoppolo threw on the sidelines a few times, he said after the game that it was just part of the routine he developed as the backup to Tom Brady with the Patriots.

Shanahan said Sunday that he had no intention of putting Garoppolo in the game for any reason other than an injury to Beathard, and indicated Monday that again will be the plan for this week's game against the New York Giants.

While the injuries have piled up throughout the roster, Shanahan said Beathard came out of the game relatively healthy considering he took five sacks and was hit a total of 16 times.

"He's OK," Shanahan said. "I know he's sore today. Hopefully he'll be better by Wednesday but no serious injuries."

Beathard managed to finish the game against Arizona despite all those hits, going 24-of-51 for 294 yards with an interception for a passer rating of 57.1.

For his part, Garoppolo acknowledged Sunday that the past week has been a whirlwind as he has attempted to learn Shanahan's offense quickly enough to play if called upon. He spent most of Sunday attempting to take the playcalls he heard through his helmet and go through them mentally as they unfolded on the field.

"Some of the calls I know and some I don't right now, so I was just trying to get as much as I can as fast as I can," Garoppolo said. "It's a process, so I'm just working every day to get better."

While Garoppolo does that, the 49ers are hoping to get healthier so that if and when Garoppolo's time comes, he has a more capable supporting cast. After this week's game against the Giants, the Niners are scheduled to have a bye before returning to play Seattle at home on Nov. 26, which remains a logical target date for Garoppolo's debut.

On Monday, starting free safety Jaquiski Tartt (broken arm) and backup tight end Cole Hikutini (knee) were placed on injured reserve. Backup offensive tackle Garry Gilliam (knee) will go on IR in the next 24 hours or so, meaning the Niners will have placed a league-leading 23 players on IR since the start of training camp.

Shanahan also ruled out reserve linebacker Elijah Lee (knee), receiver Trent Taylor (ribs) and tight end George Kittle (ankle) for this week against the Giants.

All of those injuries come on the heels of a week in which the Niners lost receiver Pierre Garcon (neck) and free safety Jimmie Ward (broken arm) for the season. Left tackle Joe Staley (eye), guard Brandon Fusco (biceps), end Aaron Lynch (calf), defensive tackle D.J. Jones (knee), cornerback Dontae Johnson (shoulder), fullback Kyle Juszczyk (neck) and defensive end Solomon Thomas (knee) are also still on the mend, though Shanahan said they'd all be monitored this week.

In the meantime, the 49ers will be making more roster moves in the next couple of days just to have 46 healthy players available this week. The team has already signed veteran receiver Louis Murphy and tight end Logan Paulsen, both of whom have spent time with San Francisco this year.

"We plan to sign some guys here over the next couple of days," Shanahan said. "They're working on it right now into tomorrow. We're going to have to figure that out by Wednesday."