DETROIT — The NFC might have a nasty new rivalry.
After the San Francisco 49ers knocked Detroit from the unbeaten ranks 25-19 Sunday in a game that matched the pregame hype, both coaches bumped each other in an emotionally charged exchange. The incident came after 49ers coach Jim Harbaugh's exuberant celebration and black-slap of Lions coach Jim Schwartz as they met on the field.
Alex Smith's fourth-down, 6-yard pass to Delanie Walker gave San Francisco (5-1) the go-ahead touchdown with 1:51 left. The play stood after video review didn't show definitely whether Walker's right knee was down before the ball reached the goal line.
Harbaugh, a first-year NFL coach who played at Michigan, came across the field toward Schwartz pumping his right fist. The coaches spoke very briefly, then bumped into each other and had to be separated more than once.
Harbaugh seemed to say something that fired up Schwartz, who charged after him as both teams were going toward the tunnel. 49ers and Lions gathered, appearing to keep the peace — probably because they were worn out from a hard-hitting, penalty-filled game with three lead changes after halftime.
David Akers gave San Francisco a six-point lead with 1:02 to go with a 37-yard field goal.
Detroit (5-1) had a chance to drive for a tying field goal or a go-ahead TD, but couldn't get a first down against a swarming defense that hit and confused quarterback Matthew Stafford from the start. That last drive started with San Francisco's fifth sack and ended with a catch and lateral — 69 yards short of the end zone.
Smith lost a fumble on his first snap and threw an interception late in the third quarter, matching his turnover totals from the first five games in both categories. But he made a clutch pass to Walker for the win.
Smith was 17 of 32 for 125 yards, going early and often to Michael Crabtree, who matched a career high with nine receptions for 77 yards. Frank Gore ran 15 times for 141 yards, including a season-long 55-yard gain, and scored a TD that pulled the 49ers within three after they were outscored 10-0 in the first quarter.
Stafford looked shaky for the first time this season; San Francisco had a lot to do with that. He was 28 of 50 for 293 yards with two TDs. One of the times he was sacked was in the end zone, giving the 49ers a safety that cut their deficit to one point midway through the second quarter.
Jason Hanson missed a 52-yard field goal that would've given Detroit a four-point lead late in the first half, then Akers made a 55-yard kick to match a season high. That put the 49ers ahead 12-10 as time expired in the half.
Brandon Pettigrew had eight catches for 42 yards and a score. Calvin Johnson added seven receptions for 113 yards but didn't score after being the NFL's first player with nine TD receptions in the first five games of a season.
Stafford connected with Nate Burleson on a 5-yard pass into the end zone ruled incomplete on the field. It was overturned after video review, giving Detroit a four-point lead early in the fourth quarter. Burleson caught the ball and got both feet down, then lost the ball after tumbling beyond the end zone — a play similar to Johnson's well-documented catch that was ruled incomplete last year at Chicago.
The Lions couldn't get a running game going with either Jahvid Best or Maurice Morris against a sturdy front and perhaps the league's best linebacking corps, allowing the 49ers to hit and harass Stafford.
The 49ers overcame 15 penalties, including five false starts at raucous Ford Field, and Detroit drew six flags.