Jimmy Garoppolo returns, but Trey Lance, Javon Kinlaw, Maurice Hurst all out Sunday for San Franc...

SANTA CLARA, Calif. -- After a three-week hiatus, Jimmy Garoppolo is set to return as theSan Francisco 49ers' starting quarterback on Sunday night.

Niners coach Kyle Shanahan said Friday that Garoppolo's right calf has healed enough for him to start against the Indianapolis Colts. That announcement came after Garoppolo returned to practice on Monday and took most of the reps the rest of the week.

"He got better each day and I see him as 100 percent now," Shanahan said.

But the Niners will be without several key players against the Colts. Backup quarterback Trey Lance (knee) and defensive tackles Javon Kinlaw (knee) and Maurice Hurst (calf) have all been ruled out.

Starting left tackle Trent Williams is listed as doubtful because of elbow and ankle injuries.

"It's stemming from the Cardinals game," Shanahan said of Williams' ankle injury. "We didn't think it was as bad as it obviously is ... He zinged it a little bit in practice on Monday and he hasn't been able to go since. For Trent, of anybody on this team, we'll take it all the way up to game time."

While Garoppolo is back in the mix, Lance, who filled in for Garoppolo in a Week 5 loss to Arizona, will not be available against Indianapolis. Lance is dealing with a sprained left knee and did not practice all week, though the Niners are hopeful he'll be back next week.

Veteran Nate Sudfeld will again be elevated from the practice squad to serve as Garoppolo's backup. Garoppolo suffered the calf injury early in an Oct. 3 loss to the Seattle Seahawks.

After that game, Garoppolo quickly self-diagnosed the injury, saying he hoped it would be only a couple of weeks. That turned out to be accurate, as Garoppolo missed only the Arizona game because the Niners had a Week 6 bye.

"That 'couple of weeks' thing was a little aggressive, came out the gate with that," Garoppolo said. "I've done it before in the past, similar injuries to that. So, it was I just kind of knew my body and knew it was going to take a couple of weeks. It was just a little pull. It wasn't anything too serious."

As he worked his way back from the injury, Garoppolo stayed near the team facility, rehabbing with an eye toward playing against Indianapolis. The biggest thing, according to Garoppolo, was getting back to a point where he could make minor adjustments in the pocket without concern for aggravating the injury.

"Pushing off of it, just those quick, little jerky movements, I guess you could say," Garoppolo said. "I just didn't want to push it too much last week, but I think during the bye week we've really made some big strides, so I'm happy with where it's at."

If Williams is unavailable, the 49ers will turn to rookie Jaylon Moore as the starting left tackle. The absences of Hurst and Kinlaw leave the Niners a bit thin on the interior of the defensive line, with D.J. Jones, Kentavius Street, Zach Kerr and, on occasion, Arik Armstead the only healthy options to handle the two inside spots.

Shanahan said the team will also activate running back JaMycal Hasty from injured reserve. He has been out since Week 2 because of a high ankle sprain.