SANTA CLARA, Calif. (AP) — For most of the first half, it looked as if the banged-up San Francisco 49ers were poised to head into their bye week with seven straight wins and an undefeated record.

Then the impact of the absences of key players mounted, they couldn't hold onto the ball and then gave a game away to the Atlanta Falcons in a 29-20 loss Sunday that will sting for the next week for everyone from coach Kyle Shanahan on down.

“I think it’s going to sour everybody’s week, Kyle’s week,” tight end George Kittle said. “He’s probably just angry at the world. But like everybody else. I’m not going to be incredibly happy the entire time. But I think that’s good.”

Despite missing almost all of their top receivers, the 49ers (6-1) scored touchdowns on two of their first three drives to take a 14-3 lead. That's when the game turned with Christian McCaffrey hobbled by a strained hamstring.

Kaelon Black lost a fumble with San Francisco driving for another score, Brock Purdy threw two interceptions in the second half and Kittle lost a fumble late that sealed the first loss of the season for the Niners.

San Francisco had the ball inside the Falcons 30 on five of its final six drives and scored on just one of them, also getting stopped on one fourth down.

“I think our guys know the mistakes we made,” Shanahan said. “Anytime you have four turnovers to zero, it’s really hard to win in this league.”

In all, it's been a successful start to the season for the 49ers, despite injuries to several key players. They won the opener in Australia against the Los Angeles Rams and a Week 5 road game against defending champion Seattle to head into the bye week in first place in the NFC West.

They hope to get several key players back when they return next week or soon after, including receivers Mike Evans, Deebo Samuel and Demarcus Robinson, and defensive end Nick Bosa.

But they know there's more work to do in the second half of the season.

“Unfortunately, we’re not going undefeated this year. That’s how I look at it,” linebacker Fred Warner said. “It’s not just about winning. We have to continue to get better as a team. I feel like today we didn’t get better; we took a step back. That doesn’t mean that we can’t use this vibe the right way, get healthy, get our mind right for what we have ahead of us and be better going forward. I’m excited about the challenge.”

What’s working

Stopping explosive runs. San Francisco has been the stingiest defense when it comes to preventing long runs and that held up against Bijan Robinson on Sunday. Robinson's longest run was 12 yards as the Niners did a good job bottling him up. The Niners have allowed a league-low five runs of at least 10 yards this season.

What needs help

Special teams. Kicker Eddy Pineiro missed his fourth extra point of the season to go along with his three missed field goals for a league-worst seven missed kicks. The kick coverage also struggled, allowing returns of 61 and 38 yards to set up two scores for Atlanta.

Stock up

Black as a runner. Despite the lost fumble, Black showed good flashes in the game as the backup to McCaffrey. The rookie led the team with 63 yards rushing and scored on a 30-yard run that was the longest touchdown run for San Francisco since the 2023 season.

Stock down

Pass rush. After having their first back-to-back games with at least four sacks, the Niners struggled to get pressure on Michael Penix. They had no sacks and just three pressures, according to Pro Football Focus. San Francisco is hoping to get a boost if Bosa can return after the bye. He has missed the past five games with a calf injury.

Injuries

Shanahan said he was optimistic that McCaffrey could play when the Niners return from the bye. ... DB Upton Stout (shoulder) was active but didn't play Sunday but should be ready after the bye week.

Key number

49. The 49ers have trailed by at least 10 points in the fourth quarter 49 times in the regular season and playoffs under Shanahan and have lost all of them. Every other team has at least one double-digit comeback in the fourth quarter in that span. The most recent time San Francisco did it came in Week 16 of the 2016 season against the Rams with Chip Kelly as coach.

Next steps

The 49ers have the week off before hosting Las Vegas on Nov. 8.