Jim Harbaugh charged across the field, lifting his shirt to expose his belly to attempt a chest bump. He extended his right hand to Jim Schwartz for a shake and slapped him on the back with his left hand.
Schwartz didn't like what was done or said - claiming he heard an expletive - and went charging after Harbaugh. What an emotion-filled scene following a meeting of turnaround teams that matched pregame hype in San Francisco's 25-19 victory over Detroit on Sunday.
The NFC might have a nasty new rivalry no one saw coming.
After the 49ers knocked the Lions from the unbeaten ranks on Alex Smith's touchdown pass with 1:51 left, both coaches added some highlights - or lowlights - of their own.
Harbaugh took the blame in one breath - and a shot in the next.
"That's totally on me," Harbaugh said. "I shook his hand too hard."
NFL spokesman Greg Aiello said the incident will be reviewed.
Harbaugh, a first-year NFL coach who played at Michigan, had to be separated from Schwartz more than once after Schwartz came running and lunging toward him as both teams were going to the tunnel.
"I went to congratulate coach Harbaugh and got shoved out of the way," Schwartz said. "I didn't expect an obscenity at that point. Obviously, when you win a game like that, you are excited, but there is a protocol that goes with this league."
Players from the 49ers (5-1) and Lions (5-1) gathered and appeared to restore order - probably because they were worn out from a hard-hitting, penalty-filled game with four lead changes after halftime.
"Ironically, I was playing peacemaker," Detroit defensive end Kyle Vanden Bosch said. "But this is an emotional sport."
Smith's fourth-down, 6-yard pass to Delanie Walker gave San Francisco 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.
David Akers gave San Francisco a six-point lead with 1:02 to go with a 37-yard field goal.
Detroit had a chance to drive for a winning 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 - to trigger Harbaugh's exuberant celebration.
"It fires me up a lot," Harbaugh said. "If that offends you or anybody else, then so be it."
San Francisco lost its first five games last season and the five-time championship franchise failed to finish with a winning record for the eighth straight year. Harbaugh has made an instant impact, quickly changing culture with many of the same players. The NFC West-leading 49ers have won five of their first six games for the first time since 1998.
"He loves football," Smith said. "He's an emotional guy, and it's showing up on this team."
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 the No. 1 pick overall from the 2005 draft made a clutch pass to Walker for the win when Michael Crabtree drew away the defense.
"They kind of jumped Crab and left me open in the middle," Walker said. "Alex made a great read and made a perfect throw."
Smith was 17 of 32 for 125 yards, going early and often to 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 and San Francisco had a lot to do with that.
"It's a good defense," he acknowledged.
Stafford was 28 of 50 for 293 yards with two TDs.
Detroit had won nine straight regular-season games, dating to last season, in what was the league's longest active streak.
"We had trouble getting guys free, and when we did, we didn't always make the throws," Schwartz said. "We need to get the running game going so that we don't look quite so one-dimensional."
The Lions couldn't move the ball on the ground 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.
He was sacked once 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. Akers made a 55-yard kick to match a season high, putting 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 49ers overcame 15 penalties, including five false starts at raucous Ford Field, and Detroit drew six flags.
"Once you get a couple false starts, it's like throwing gasoline on a fire," Smith said.
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.