SAN FRANCISCO — As Ahmed Plummer raced downfield for his game-breaking interception return, a white-haired man with a headset ran right along with him.
Dennis Erickson promised more aggression and enthusiasm when he took charge of the San Francisco 49ers. The new coach backed up those words with a joyful sideline sprint that was one of countless high points in his 49-7 debut victory Sunday over the bumbling Chicago Bears.
Erickson admitted to a serious case of butterflies before the game, but his team showed no nerves while flattening the Bears for their biggest victory since 1989. San Francisco forced five turnovers, outgained Chicago 391 yards to 127 and filled a highlight reel with big plays on offense, defense and special teams.
The 49ers scored 23 points during an impressive rally in the final 6:01 of the first half, turning it into a blowout. In the locker room afterward, Terrell Owens and defensive coordinator Jim Mora presented Erickson with the game ball.
"To be honest, you can't ask for a better start," Erickson said. "We blitzed a lot, we came after them . . . and everybody did their job. It was a great team effort."
The 49ers took a 33-7 halftime lead with their biggest offensive output in a half since 1992. Erickson left in nearly all of his starters to finish two fourth-quarter drives.
The highlights were numerous. Jeff Garcia passed for 229 yards and two touchdowns, and Garrison Hearst caught a TD pass and rushed for another score. Plummer returned an interception 68 yards for a score, and Jimmy Williams and Brandon Lloyd made exceptional special-teams plays.
Tai Streets had a TD catch, Owens caught seven passes for 112 yards, Plummer had two interceptions and Jeff Chandler kicked five field goals.
"It was a great feeling. It was like we were running downhill all day," said Williams, who had an interception and forced a fumble. "We just got on a roll, and everybody made one big play after another."
The Bears were finished early in their worst defeat since a 47-0 loss at Houston on Nov. 6, 1977. Chicago floundered at every level in quarterback Kordell Stewart's first game since leaving Pittsburgh.
Stewart, who infuriated Steelers fans for eight years with erratic performances, went 14-of-34 for 95 yards, missing open receivers and forcing balls to covered ones. He was under constant pressure from the 49ers' blitzing defense, and his teammates dropped passes and missed blocking assignments with alarming frequency.
"I'm embarrassed," All-Pro linebacker Brian Urlacher said. "That was the worst game we've played since I've been here. When it goes bad, it goes bad. We just didn't play well."
During two dominant scoring drives in the first quarter, the 49ers showcased several of the aggressive innovations promised by Erickson. San Francisco employed a variety of formations, including sets with five receivers or two tight ends.
Chicago only showed signs of life during a brief stretch of the first half. Mike Brown intercepted Garcia's poorly thrown ball inside the 49ers 15, setting up Stewart's 3-yard pass to Desmond Clark.
The defense then forced a punt, but Williams forced and recovered rookie Bobby Wade's fumble at the Chicago 6. Garcia scored on a 3-yard run.
Then Lloyd, a rookie receiver who had an outstanding camp, blocked Brad Maynard's punt at the 18. Streets caught a pass across the middle and scored.
"After a defeat like that, you don't feel good about anything," Chicago coach Dick Jauron said. "It just snowballed. ... I know that there are some things on film that will show up that are going to be OK, but it just seemed like nothing went right."
Stewart got the Bears into San Francisco territory in the final minute before halftime. But his inept throw behind two receivers was picked off by Plummer, who returned it untouched for his first career touchdown.
Williams then intercepted Stewart with 18 seconds left, setting up Chandler's half-ending field goal. The crowd at Candlestick Park gave a lengthy standing ovation as the 49ers left the field.
"We took advantage of what they gave us, and you saw what happened," Owens said.