SANTA CLARA, Calif. -- After observing Christian McCaffrey participating in the San Francisco 49ers' most strenuous practice of the week, coach Kyle Shanahan said he has seen enough to believe that the star running back will make his season debut Sunday.

Speaking to KNBR radio in San Francisco on Thursday, Shanahan said McCaffrey has done well enough in practice this week to return against the Tampa Bay Buccaneers.

"He's been awesome these last two days," Shanahan said. "You never know [about] a setback or anything, but these two days have been great, and I expect to see him out there."

McCaffrey has been on injured reserve since Sept. 14 because of bilateral Achilles tendinitis that followed a calf injury that began to bother him in early August. McCaffrey traveled to Germany to meet with a specialist while the 49ers were in Los Angeles to play the Rams on Sept. 22.

Before last week's bye, Shanahan said McCaffrey would stick around the team facility and do simulated practice activities that would lead to his return to practice. There were no setbacks from that, which led to the practice window opening Monday.

McCaffrey took part in the team's "bonus" practice that day and has since participated on a limited basis in sessions Wednesday and Thursday. But the Thursday practice was always thought to be the most important; it's the one padded session of the week and the longest.

Now, all that stands between McCaffrey and his season debut Sunday is a lighter Friday practice that is a little more than a walk-through and then a cross-country flight to Tampa, Florida, on Friday evening. Barring any issues there, the Niners would then activate McCaffrey from injured reserve Saturday.

To make room for him on the roster, they will need to make a corresponding move to open a spot.

For the better part of the past few weeks, Shanahan and the Niners have pointed to this week for McCaffrey's potential return as he continued the rehab that kept him out of the team's first eight games.

McCaffrey's return to practice has offered a notable boost for the 4-4 Niners, according to coaches and teammates.

"It's been awesome," quarterback Brock Purdy said. "Just what he brings to the table and really just firing everybody else up around. All of us coming off the bye week and feeling good and fresh and then you get 2-3 next to you in the backfield, it's been awesome. Looks great moving around and he's trending in the right direction. So, we're excited to see what happens."

Assuming McCaffrey does play against Tampa Bay, it remains to be seen if he will take his usual workload. When healthy, McCaffrey has been the team's primary back, racking up a career-high 417 touches (including playoffs) on his way to winning the league's Offensive Player of the Year award in 2023.

Jordan Mason, who stepped in for McCaffrey and ranks third in the NFL in rushing yards per game, offers depth, but he, too, was limited in practice Thursday because of an ongoing shoulder injury. Rookie Isaac Guerendo and veteran Patrick Taylor Jr. are the other backs on the 53-man roster.

Despite those options, Shanahan has indicated that McCaffrey's workload will be determined by how he feels as the game nears and noted Wednesday that he does not believe McCaffrey's injuries are the result of being overworked in previous seasons.

"I think things happen to a body," Shanahan said. "I think they happen in offseason, but I don't think that really has to do with numbers. When a guy is healthy and good, they're usually good. But we've got to see where his conditioning is at, how he is. I know he is conditioned as well as he can be, but how his football conditioning is and stuff. But usually, I don't chalk up to numbers one year to affect the injury the next year."

If things go according to plan, Shanahan also indicated to KNBR that a pair of other key Niners -- receivers Jauan Jennings (hip) and Deebo Samuel (rib, oblique) -- are also expected to play against the Bucs.