SANTA CLARA, Calif. – In what is the most important step he has taken in his recovery from Achilles tendonitis, San Francisco 49ers running back Christian McCaffrey returned to practice.

The Niners officially opened McCaffrey’s 21-day practice period Monday afternoon, meaning he has three weeks to prove he’s ready to be activated from injured reserve to the 53-man roster.

Sure enough, McCaffrey was on the practice field warming up with his teammates for about a two-minute viewing period, open to the media. For his teammates, McCaffrey’s return was a welcome sight, with one noting that McCaffrey’s fresh legs saw him progress quickly compared to everyone else during a team exercise.

“It’s such a great feeling to see that 2-3 out there doing his extended warm-up and a million high knees that he does before practice,” left tackle Trent Williams said. “It was great to see him.”

While McCaffrey and the 49ers will have time to see how he fares in practice before using him again in games, there is optimism around the team that he will be available on Sunday against the Tampa Bay Buccaneers as long as this week goes well .

For much of the past few weeks, the Niners have been hinting at McCaffrey’s potential return this week as he continues to deal with the tendonitis that kept him out of the team’s first eight games.

Before San Francisco’s bye last week, coach Kyle Shanahan again suggested McCaffrey start practice Monday as long as his simulated practice work last week didn’t have any setbacks.

“As long as everything goes well, hopefully we’ll get him back in practice next week,” Shanahan said on Oct. 28.

McCaffrey originally went to injured reserve on September 14 after dealing with tendonitis and a calf injury that hampered him in early August. While McCaffrey recovered from the calf problem, the Achilles tendonitis lingered and eventually led McCaffrey to travel to Germany to meet with a specialist while the 49ers were in Los Angeles to play the Rams on September 22.

While backup Jordan Mason has done well in McCaffrey’s place — Mason is third in the league in rushing yards per game (85.6) and sixth in yards per carry among running backs (5.1) — the Niners struggled to end drives in the red zone. They rank 28th in the NFL in red zone touchdown percentage, scoring inside the opponent’s 20 on 48.6% of drives.

McCaffrey scored 21 total touchdowns in 2023 en route to Offensive Player of the Year honors.

“(You) could probably catch him in any foul, it’ll make them better,” Williams said. “Obviously our offense is tailored around him and some of his strengths, so it will definitely be a huge boost for us.”

Shanahan indicated last week that McCaffrey’s workload upon his return will also depend on how he looks in practice.

“The expectation is to see how he does when he comes back and then evaluate him as he goes,” Shanahan said last week. “The hope is of course that everything will just go back to normal and that it will be perfect. That is what we all strive for, but you have to play it smart and you have to evaluate that every day. What we do with our own eyes we see what he shows us That will be something we continually work on.”

The 49ers also opened the practice window for offensive lineman Jon Feliciano on Monday. Feliciano missed the first half of the season with a knee injury. Receiver Jauan Jennings (hip) and kicker Jake Moody (sprained right ankle) were also back on the practice field Monday, and Williams offered some hope that linebacker Dre Greenlaw could open his practice window soon as he continues to recover from the torn Achilles tendon he suffered. in February’s Super Bowl.

“Definitely super happy for (McCaffrey) that it turned around the corner and he was able to get back out there and do what he loved,” Williams said. “I even saw a glimpse of Greenlaw sprinting around there with a helmet on. They were both excited when we saw that.”