Undefeated but battered, the San Francisco 49ers limp into Atlanta to face the reeling Falcons on Sunday afternoon.

San Francisco (6-0) has paid a physical toll for its best start since 2019, when it won its first eight games. The 49ers could be without receivers Deebo Samuel (hamstring) and Mike Evans (Achilles), who missed Wednesday's walkthrough, while Christian Kirk (calf) is working toward a return from injured reserve entering a trip that will send the team away from the West Coast for the first time since a season-opening game in Australia.

After beating the Washington Commanders on Monday night, head coach Kyle Shanahan's team will face a short week of practice and will need to keep relying on quarterback Brock Purdy.

The 26-year-old's 14 passing touchdowns are tied with Kirk Cousins and Trevor Lawrence for most in the NFL, while his QBR of 83.0 is best in the league.

Shanahan and first-year defensive coordinator Raheem Morris will return to familiar territory. Shanahan was Atlanta's offensive coordinator in 2015 and 2016, helping the Falcons reach Super Bowl LI, while Morris was fired in January after two consecutive 8-9 seasons as Atlanta's head coach.

"I don't think they can be more motivated. I think our guys are as motivated as you can get each week," Shanahan said when asked if his players wanted to specifically win for Morris on Sunday. "I don't think we get too caught up in that, but I know they care about Raheem a lot and definitely would want to do that for him. But I don't think we're looking at it as too much of a personal game."

Shanahan will have his team focus on stopping dual-threat Atlanta running back Bijan Robinson, who has 641 rushing yards and five touchdowns (four rushing, one receiving).

"It'll be a huge challenge going against Bijan," Shanahan said. "He's as good as advertised in the pass game and run game. He doesn't have any weakness, so it's a huge challenge for our linebackers, huge challenge for our whole defense."

Meanwhile, Atlanta (2-4) will look to salvage a three-game homestand against a third straight contending team. The Falcons, off to their worst six-game start since 2020, have dropped consecutive one-score games to the Baltimore Ravens and Chicago Bears before facing a San Francisco team that has won its first six games.

"They're undefeated for a reason," Atlanta head coach Kevin Stefanski said of San Francisco. "Very well-coached, very good players, so it's an awesome challenge for this football team. We have to play our best. That's the truth; we've got to play our best on Sunday."

Atlanta's pass defense has struggled to limit opposing quarterbacks. The Falcons rank 28th in the league, allowing 252.0 passing yards per game. Stefanski doesn't think that obstacle will get any easier this week.

"(Purdy) is a very, very special quarterback," Stefanski said. "I haven't studied the rest of the league -- I'm watching a lot of his tape right now -- but it's hard to imagine someone is playing the position better than he is right now. He's an elite processor, he has elite accuracy and I think he's an elite scrambler. ... Very smart, hard to get on the ground. This is a great player."

Atlanta cornerback Billy Bowman Jr. (hamstring) and linebacker Divine Deablo (forearm) didn't practice on Wednesday. Starting cornerback A.J. Terrell returned to practice for the first time since injuring his groin on Sept. 20. Rookie linebacker Kendal Daniels was a full participant Wednesday after leaving Sunday's game against Chicago on a stretcher with a neck injury.

San Francisco defensive end Nick Bosa (calf) also missed Wednesday's walkthrough, although Shanahan expressed hope that the five-time Pro Bowler could return Thursday

Bosa hasn't played since Week 2.