Skidding 49ers might be without Brock Purdy for Bengals’ visit

The San Francisco 49ers, who captured the first five games of the season to extend their franchise-record, regular-season winning streak to 15, are suddenly riding a two-game skid as they face the Cincinnati Bengals on Sunday in Santa Clara, Calif.

The 49ers (5-2) are coming off a 22-17 road loss against the Minnesota Vikings on Monday night.

The offense was again led by running back Christian McCaffrey, who totaled 96 yards from scrimmage and two touchdowns. San Francisco was without starting left tackle Trent Williams (ankle) and wide receiver Deebo Samuel (shoulder), both of whom remained sidelined for practice on Wednesday.

Despite playing through an oblique injury, McCaffrey has scored 11 TDs in 2023, tied for the NFL lead with the Miami Dolphins’ Raheem Mostert.

With one touchdown on Sunday, McCaffrey would match the all-time NFL record for consecutive games with a touchdown at 17 games (regular season and postseason combined). Lenny Moore set the mark with the Baltimore Colts in 1963 and ’64.

Even though he scored twice on Monday, McCaffery took responsibility for contributing to San Francisco’s loss due to a first-quarter fumble in the red zone.

“Anytime you lose, it’s a bad feeling,” McCaffrey said. “I think we have a team that’s hypercritical of each individual. We can’t just let it trickle down. Got to take a good, hard look in the mirror. I know I’ll do that. I made a bad mistake that I believe cost us the game if I don’t fumble that ball. Put it on me. Go from there.”

San Francisco quarterback Brock Purdy threw for 272 yards and a touchdown but took a second straight loss after opening his career with 10 straight regular-season wins. However, he missed practice on Wednesday while in the NFL’s concussion protocol, putting in doubt his availability for Sunday.

Sam Darnold would step in to make his first start for San Francisco if Purdy isn’t ready to face the Bengals. Darnold, 26, has a career 21-34 record as a starter for the New York Jets and the Carolina Panthers.

Niners coach Kyle Shanahan said, “I have as much confidence in Sam as I could have in someone that I haven’t gone into a real game with. He was great in the offseason. He has been great here in these seven weeks so far. He’s already ready to go.”

The 49ers are averaging 28.7 points, second only to Miami (34.3) in the NFL.

The Bengals (3-3) return from their bye week looking to earn a third straight win and complete a sweep of the NFC West. After a 1-3 start, Cincinnati posted a road victory over the Arizona Cardinals in Week 5 and a home win against the Seattle Seahawks in Week 6.

In their latest game, the Bengals held off Seattle on four different trips inside the 10, including two drives in the final three minutes, to secure a 17-13 win. Cincinnati intercepted Geno Smith twice and recorded four sacks on the day to earn the win.

“We kind of stubbed our toe starting this race off, and we’re going to continue to pick up steam,” Bengals coach Zac Taylor said. “There’s days where our defense is going to lead the charge, lead us to victory, and there’s times where the offense is going to reciprocate that. There’s times special teams is going to take over.

“I think good teams just find ways to do it, and right now we’re at that 3-3 mark. We get a chance to get healthy and then hit the surge after the bye, starting with San Francisco.”

Linebacker Akeem Davis-Gaither (knee) was the only Bengal who sat out practice on Wednesday.

The Sunday game kicks off a stretch of five straight for the Bengals against teams that enter Week 8 with a record of .500 or better.

The 49ers lead the all-time series 13-4, including their wins in Cincinnati’s first two Super Bowl appearances. This weekend’s matchup is just the second visit to Levi’s Stadium for the Bengals, who claimed a 24-14 win at Santa Clara in 2015.