KANSAS CITY, Mo. (AP) -- Trent Green was cleared to drive this week, so he joined his Chiefs teammates on the sideline Sunday. Out on the field, Damon Huard was obviously happy to have him riding shotgun.
Getting advice and encouragement from Green and even suggestions on which plays to run, Huard and the rest of the Kansas City Chiefs played almost flawlessly in a surprising 41-0 rout of San Francisco (1-3).
"Trent's the best," said Huard, a journeyman who'd hardly done anything but carry a clipboard for six years until Green was knocked unconscious with a severe concussion Sept. 10.
"He's always got a smile on his face. He's always had some great advice and something to offer. It was nice to have him out there today."
Huard hit 18 of 23 passes for 208 yards and two touchdowns, missing only two of his first 15 tosses as the Chiefs (1-2) roared to a 24-0 halftime lead en route to their first shutout in almost four years.
The nearly airtight pass protection helped. While compiling a 133.3 passer rating -- 158.3 is perfect -- Huard was hardly ever touched or even hurried by a San Francisco defense which had rung up 12 sacks in its first three games.
"What a great veteran offensive line," Huard said. "There are so many guys that make my job easy. And our defense -- are you kidding me?"
The revamped and obviously improved Kansas City defense held Alex Smith to 92 yards passing and the 49ers to 93 yards rushing. In their first three games, the 49ers had given up only four sacks.
But the Chiefs took Smith down five times.
"It's pretty discouraging," 49ers coach Mike Nolan said. "That's a pretty tough loss. I would say that's the most difficult loss in the year and a half that I have been here. I didn't see lack of effort. I saw a lot of poor play."
Green, who is out indefinitely, was not shy in calling plays.
"He's a great play-caller," coach Herm Edwards said. "It was great all week to have him around. He's one of our leaders on our team."
Dante Hall scored Kansas City's final touchdown on a 60-yard punt return, giving him 11 touchdown kick returns in his career.
Larry Johnson rushed for 101 yards and two touchdowns for the Chiefs, who handed the 49ers their first shutout since 2004 and only their second since 1977.
The Chiefs' defense has not allowed a touchdown in two straight games.
"We just came out here and played all-out and played with our heart," said rookie defensive end Tamba Hali, who had one of the sacks. "We're going to let teams know that we have a good defense."
Tony Gonzalez passed a couple of NFL milestones. The 10-year veteran caught a 14-yard toss during the Chiefs' second touchdown drive and moved past Ozzie Newsome for second all-time among NFL tight ends with 663 receptions. He also passed Jackie Smith for third all-time in career receiving yardage at his position.
Huard hit Hall with a 13-yard touchdown pass in a 10-play, 73-yard drive on the Chiefs' first possession.
Then the 49ers gave a preview of things to come on their first four plays, following up a sack and a delay-of-game penalty with Frank Gore's fumble. Jared Allen recovered and it led to Lawrence Tynes' 22-yard field goal.
San Francisco cornerback Shawntae Spencer had a terrible day. He made his first bad mistake when he was flagged for pass interference against Hall in the second period, a 19-yard penalty followed by Johnson's 1-yard TD.
His second big mistake came one play after Smith, who had thrown 115 passes this season without an interception, got picked off by Sammy Knight.
Eddie Kennison got behind the third-year cornerback on a fly pattern and beat him down the sideline for a 34-yard touchdown pass and a 24-0 lead.
Johnson's 2-yard TD run put the Chiefs on top 34-0 early in the fourth.
It was the first shutout for the Chiefs defense since Dec. 1, 2002.
"I think it was embarrassing. It was definitely frustrating," Smith said. "We need to learn from this."
It was the 19th shutout in Chiefs history. The 49ers had not been shut out since Sept. 26, 2004 in a 34-0 loss at Seattle. The last time before that was 7-0 on Oct. 7, 1977, against Atlanta. ... First-and second-year quarterbacks since 1994 are 2-18 in their first visit to Arrowhead Stadium. ... The paid attendance was 77,609, but there appeared to be an unusually high number of empty seats, attributable at least in part to the NASCAR race going on at Kansas Speedway a few miles away.