That's because Garoppolo suffered what a source told ESPN's Adam Schefter was a torn ulnar collateral ligament of the right thumb, as well as a fracture in the same thumb, early in Thursday's 20-17 loss to the Tennessee Titans. His status for Sunday's game against the Houston Texans remains uncertain.
Garoppolo did not participate in the Niners' Monday "bonus" practice, which came after the team went its separate ways for the three days following the loss in Nashville. Rookie quarterback Trey Lance took all of the work with the starters in Monday's session, which coach Kyle Shanahan described as a walk-through.
According to Shanahan, Garoppolo suffered the injury when Titans defensive tackle Denico Autry sacked him for a 7-yard loss with 3:56 left in the second quarter. Garoppolo finished the game but struggled with a pair of costly interceptions and missed a would-be touchdown throw to open fullback Kyle Juszczyk in the first half.
Shanahan indicated that Garoppolo was hampered by the thumb on the Niners' first offensive play of the third quarter, a pass intended for receiver Deebo Samuel that sailed into the waiting arms of Titans safety Amani Hooker for an interception that Tennessee turned into the game-tying touchdown.
Garoppolo finished 26-of-35 for 322 yards with a touchdown and two interceptions for a 44.4 QBR.
"We knew his thumb was hurting him," Shanahan said. "We thought he jammed it sometime in the game, so he tells us right when he comes to the bench."
With Garoppolo considered day-to-day, Lance could be in line for his first extended work with the starters since before a Week 5 loss to Arizona. And if Garoppolo is unable to heal well enough to play Sunday, Lance would make his second career start against Houston.
Shanahan indicated the decision will come down to not only how Garoppolo feels but also how he looks throwing the ball if he progresses to that stage. As for Lance, Shanahan said the No. 3 overall pick in this year's draft has made good progress while running the scout team The coach pointed to improved decision-making and accuracy, among other things.
"This last month of Trey has been his best consecutive four weeks at practice since we've had him," Shanahan said. "He's had a number of good days and he's had some bad days like most guys do, but as far as his consistency and stuff, I feel this last month has been his best."
In addition to Garoppolo, the 49ers had some other key names dealing with injuries. Linebacker Azeez Al-Shaair has a sprained knee that will keep him out at least the next two games, according to Shanahan, while defensive tackle D.J. Jones will be limited by an ankle injury.
Finally, punter Mitch Wishnowsky is being placed on the reserve/COVID-19 list, making him the first Niner to get that designation since August.