San Francisco delivered a performance more reminiscent of a year ago when the Niners went to the Super Bowl, handing the Bears their seventh straight loss after out-gaining them by 315 yards on the way to a 24-0 halftime lead.

Purdy delivered his third 300-yard passing game of the season with two TDs to Jauan Jennings, fill-in running-back Isaac Guerendo gained 128 yards from scrimmage and scored on two TD runs and Kittle had six catches for 151 yards. That helped deliver the highest-scoring game of the season for the 49ers.

“I think we just all executed, did our job and kept it simple,” Purdy said. “I think guys weren’t overthinking anything. Just whatever was called we trusted in Kyle and executed.”

The defense did the rest with strong pressure from the four-man line that led to rookie Caleb Williams getting sacked seven times.

The Bears were looking for an emotional boost from the first in-season firing of a head coach in franchise history after letting Matt Eberflus go following a late-game clock mismanagement on Thanksgiving at Detroit.

Instead they came up on the short end of one of the most lopsided first halves in recent memory. Chicago was out-gained 319-4 in the first half for the ninth-largest discrepancy since 1991, managed only one first down and trailed by 24 points at the break.

The Bears allowed Purdy and the San Francisco offense to move down the field with little resistance with the Niners scoring three TDs and one field goal on their first five possessions.

Chicago couldn’t move the ball at all on offense, generating minus-3 yards passing thanks to four sacks and losing 37 yards on five failed third down attempts.

“We got our (butt) kicked today,” Williams said. “There’s no way around it. We got it handed to us. Offense, defense special teams, we have to come out and be better.”

Williams managed to throw two touchdown passes to Rome Odunze in the second half, but it was too late to get the Bears back into the game. Williams finished 17 for 34 for 134 yards and lost a fumble, but had his seventh straight start without an interception.

Williams’ 56 sacks this season are the most for any Chicago quarterback since the 1970 AFL-NFL merger.

INJURIES

Bears: Returner DeAndre Carter (hamstring) left in the first quarter and didn’t return. … RB Travis Homer (head) left the game in the second half.

49ers: Guerendo left the game in the fourth quarter with a foot injury. Shanahan said the team would know more about the severity on Monday. … LG Ben Bartch (high ankle sprain) left the game in the first half and didn’t return. Bartch was starting in place of the injured Aaron Banks and the Niners were forced to use third-stringer Spencer Burford the rest of the way.