DETROIT – Jim Schwartz will let Jim Harbaugh's postgame behavior speak for itself.
The Detroit coach had plenty to say, however, about the Lions' first loss of the season.
"It has been a long time -- December of last year is the last time that we've lost a football game -- so it hurts right now," Schwartz said. "We didn't play our best."
Alex Smith's 6-yard touchdown pass to Delanie Walker on fourth down gave San Francisco the go-ahead touchdown with 1:51 left, and the 49ers added a field goal less than a minute later to beat the Lions 25-19 on Sunday.
After the game, Harbaugh charged exuberantly across the field, extended his right hand to Schwartz for a shake and slapped him on the back with his left hand.
The San Francisco coach seemed to say something that fired up Schwartz, who charged after him as both teams were going toward the tunnel. The coaches had to be separated more than once. Players from both teams gathered, appearing to keep the peace -- perhaps because they were worn out from a hard-hitting, penalty-filled game with four lead changes after halftime.
"I went to congratulate coach Harbaugh and got shoved out of the way. I didn't expect an obscenity at that point," Schwartz said. "Obviously, when you win a game like that, you are excited, but there is a protocol."
That was about all Schwartz would say about the incident. NFL spokesman Greg Aiello said the league would review the incident.
"I'm sure it is on video, and you can see it," Schwartz said.
Harbaugh took responsibility for what happened but didn't provide much detail either.
"I was just really revved up," Harbaugh said. "That's totally on me. I shook his hand too hard."
Detroit (5-1) lost for the first time in 10 regular-season games, dating to last year. The Lions also won all four preseason games.
Walker's touchdown stood after video review didn't show definitively whether the San Francisco tight end's right knee was down before the ball reached the goal line.
Detroit 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.
David Akers gave San Francisco (5-1) a six-point lead with 1:02 to go with a 37-yard field goal, and the Lions did no better with their next attempt at a winning drive.
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 was 28 of 50 for 293 yards with two TDs. He was sacked in the end zone for a safety in the second quarter.
"Matt didn't have a whole lot of time today," Schwartz said. "We had a hard time getting the run game going. When it's one-dimensional that way, and I think it was, you're going to have a difficult time."
Detroit ran for only 66 yards.
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. That put the 49ers ahead 12-10 as time expired in the half.
Detroit's Brandon Pettigrew had eight catches for 42 yards and a score, and 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.
In the fourth, 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 19-15 lead. 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 play in the end zone that was ruled incomplete last year at Chicago.
The Lions couldn't hold the lead and were left to rue a couple trips deep into San Francisco territory that ended with short field goals -- one in the first quarter and another in the third.
"San Fran's got a great defense," Stafford said. "They did a great job in the red zone and held us out of some touchdowns."
The Lions couldn't get a running game going with either Jahvid Best or Maurice Morris against San Francisco's sturdy front and outstanding linebacking corps, allowing the 49ers to hit and harass Stafford.
"We're not going to go 16-0," Schwartz said. "We have to protect the quarterback better, have to run the ball better, make more plays down the field. We have to stop the run better, we have to convert field goals."
The 49ers overcame 15 penalties, including five false starts at raucous Ford Field.
Notes: San Francisco and Chicago combined for 14 false starts at Detroit, matching Houston's record from 2004 for the most false starts by visiting teams in back-to-back games since 1991, according to STATS LLC. ... The teams met with 9-1 records after being 1-9 at same point last season. ... Harbaugh played for Baltimore in 1998, when Schwartz was a Ravens assistant.