ESPN NFL

CHICAGO (AP) -- Rex Grossman showed his good and bad sides.

He fumbled another snap and had an interception returned 52 yards for a touchdown. But along with the mistakes came the moments of brilliance that have teased the Chicago Bears the past few seasons.

Grossman played the first half and passed for 211 yards and two touchdowns, and the defending NFC champions held off the San Francisco 49ers 31-28 in a preseason game on Saturday night.

Grossman led the Bears to a touchdown on the game's opening drive, a field goal on their second possession, and touchdowns on the third and fourth series. Another touchdown late in the second quarter made it 31-13 at halftime.

"You're never going to be satisfied as a football player -- and I'm definitely not -- but when you do score 31 points in a half, that's pretty good," said Grossman, who completed 13 of 20 passes but provided more fodder for his critics.

Grossman, who botched two exchanges with center Olin Kreutz on Monday night at Indianapolis, fumbled a snap during the field goal drive. And Walt Harris had that 52-yard interception return.

Although he shows Pro Bowl skills at times, Grossman can't seem to eliminate the mistakes. But the Bears (3-0) continue to do enough to win.

A defense missing Pro Bowl defensive tackle Tommie Harris, still rehabilitating from a hamstring injury suffered last December, did its part. The starters played into the third quarter, and the 49ers finished with just 206 yards.

After two sharp performances in the preseason, San Francisco quarterback Alex Smith was 4-of-8 for 47 yards before giving way to Trent Dilfer in the third quarter.

Running backs Michael Robinson and Maurice Hicks, who are sharing the rushing load while Frank Gore recovers from a broken hand, were non-factors. Robinson ran for 25 yards, while Hicks had 19.

"Adversity is what makes you better, and today we had a lot of adversity and we will learn from it," coach Mike Nolan said. "There is no excuse from the standpoint of being a preseason game or not. Third preseason game is important for all of us. We were playing last year's NFC champs, so we wanted to perform better than we did today."

A fourth-quarter rally aside, it was not a good showing for a 49ers team that has playoff aspirations after going 7-9 last season.

"In a few weeks we won't remember this, but at the same time, I think this is a little bit of a reality check for us," Smith said. "Here are the NFC champs from a year ago, a place we aspire to be."

San Francisco (1-2) could not contain Bernard Berrian, who caught three passes for 79 yards and a touchdown. But the Bears got a scare in the first quarter when wide receiver and return specialist Devin Hester left with a shoulder injury.

The Bears' running game remained in neutral after gaining 2.4 yards per carry in the first two preseason games. Cedric Benson carried 19 times for 33 yards, and Adrian Peterson ran for 27. Both scored touchdowns.

"The defenses that we've played, they're doing a good job of keeping their linebackers back and keeping them from getting attached to offensive linemen," Benson said. "They've been making a lot of plays."

With fans again debating who should start, Grossman handled the first snap flawlessly. Then he unleashed a pass that -- although underthrown -- had enough on it to reach an open Berrian along the left side for a 45-yard gain. That put the ball on the San Francisco 15 and set up a 2-yard scoring run by Benson.

Hester set up the second drive with 29-yard punt return. Then came the groans.

Hester, starting at wide receiver with Muhsin Muhammad inactive, was injured trying to block. He stayed down for a few minutes, then jogged to the sideline.

Grossman immediately connected with Desmond Clark for a 30-yarder that put the ball on the 19, but the cheers went away two plays later when the quarterback fumbled the snap. He recovered, and Robbie Gould ultimately hit a 37-yard field goal, with the ball bouncing in off the right upright, for a 10-0 lead.

"We had a couple fumbles last week, right?" coach Lovie Smith said. "We had one tonight. Making progress, that's what I see."

Said Grossman, "We sorted it out. We're going to continue to work on it and hopefully fix it."

Game notes

49ers DT Bryant Young missed his third preseason game because of a bulging disk in his back. San Francisco was also without DT Aubrayo Franklin and backup safety Dashon Goldson. ... Bears LT John Tait returned after missing the first two preseason games following offseason ankle surgery, but Chicago was without left guard Ruben Brown. ... Bears backup QB Brian Griese was 3-of-4 for 10 yards.