But if he has his way, Garoppolo will be in his usual starting spot in a game the 8-7 Niners must have in their pursuit of an NFC playoff spot. He said Wednesday he "definitely" has a chance to play against the Texans.
"I played the entire game with it basically, so it's really just about being able to grip the ball and do the things I normally do and we're gonna go test those out today, see how it feels and go from there," Garoppolo said. "But I feel confident in it."
Before Wednesday's practice, Garoppolo threw under the supervision of the team's training staff. But Garoppolo was seen walking off the field before the workout began and was officially listed as a non-participant on the participation report.
Garoppolo also did not take part in the team's Monday "bonus" practice as he waited for swelling in the thumb to subside. Wednesday is the first time he threw since the Niners' 20-17 loss to the Tennessee Titans last week.
"We'll see how it looks today," Garoppolo said Wednesday. "If it looks good, it looks good. If it looks bad, it looks bad. It's just one of those things that you have got to test it out and go through it. Until we do that, it will be hard to say. But we'll all be on the same page and we'll do the right thing for the team."
While there was some confusion about the severity of Garoppolo's injury, coach Kyle Shanahan offered more clarity on Wednesday. According to Shanahan, Garoppolo has a Grade 3 sprain of the ulnar collateral ligament in his right thumb, adding that reports of a fracture stem from the fact that the sprain "pulled off" a little fleck of his bone.
But Shanahan said Garoppolo doesn't need surgery and insisted that it's the sprain that has Garoppolo's status in doubt for Sunday.
"Whenever there's a bone that has anything off of it, you can call it a fracture, you can call it a chip, you can call it something but that really isn't what's keeping him out," Shanahan said. "It's the third-degree sprain that he has. But because it's not moving and stuff, he doesn't need surgery and he has a chance to play this week."
Rookie Trey Lance took all the reps with the starting offense on Monday and did so again Wednesday with Garoppolo out.
If Lance gets the nod, it would be only his second NFL start after he filled in for Garoppolo against the Arizona Cardinals on Oct. 10. Since 2017, the Niners are 30-14 in his starts and 7-28 in games started by all other quarterbacks.
For his part, Garoppolo said whether he plays will depend on how he's able to grip and throw the ball. He suffered the injury late in the second quarter of the loss to the Titans and finished the game, though he threw a bad interception to open the third quarter.
Garoppolo added that he tweaked his throwing motion as the game went on to compensate for the injury, though he downplayed its severity on the sideline and did not bring it up to media after the defeat.
"It's a torn ligament so it is what it is," Garoppolo said. "The pain, it's not going anywhere so I know what that feels like but it's just about being confident and going out there and being able to do what I normally do with the football. We'll see where it gets us but I feel good right now with it."
With Garoppolo dealing with the thumb injury and players going on the reserve/COVID-19 list all over the league, the Niners are also taking additional steps to protect all of their players, quarterbacks included.
Shanahan said the team also switched all meetings to virtual on Wednesday, two days after punter Mitch Wishnowsky became the team's first player to go on the COVID list since August.
"We've been pretty fortunate with it so far having just one guy down," Shanahan said. "But just watching the world and watching everybody, knowing how it's a matter of time is what it looks like so we're just trying to be careful and keep everyone separate right now until we go outside."