It marks the second fine of the season for McCree, a seven-year veteran who has never been noted in the past for his overaggressive play. He was earlier fined $7,500 for a shot to the head of Green Bay Packers wide receiver Donald Driver in a Sept. 23 game.
The play which drew the most recent fine occurred with 1:58 remaining in Sunday's game, and on the next-to-last carry for Peterson, who set a new league single-game record, rushing for 296 yards on 30 attempts. On a first-and-10 from the Minnesota 10-yard line, Peterson burst up the middle for 35 yards, and McCree pursued the Vikings' star and then yanked him down by the back of the shoulder pads.
The tackle drew a 15-yard penalty for unnecessary roughness, moving the ball to the San Diego 40-yard line, from where the Vikings ran out the clock. The league's leading rusher, Peterson was slightly shaken up on the play, but did return after sitting out one snap, to get one more carry for three yards.
The NFL banned the horse-collar tackle in May 2005 by a 27-5 vote after a proposal to take it out of the game was tabled at the league's annual meetings two months earlier. The rule passed after the competition committee twice rewrote it.
Officials have more vigorously enforced the rule on the field this season, and the league has imposed several fines against defenders who have violated it.
The ban against the horse-collar tackle is often referred to as the "Roy Williams Rule," so-called because the Dallas Cowboys' star strong safety often employed the technique in which a defender grabs a player on the back of his shoulder pads and yanks him down.
In studying the tackle, the competition committee concluded that it had contributed to several lower extremity injuries in 2004. Some felt that Williams was responsible for four significant injuries that season.
It is not known if McCree will appeal the fine. McCree, 30, has a 2007 base salary of $650,000.
McCree, who joined the Chargers as an unrestricted free agent in 2006 and immediately added stability to the secondary, has 39 tackles, three interceptions and five passes defensed in eight games this season.
In a separate incident from the same game, Minnesota defensive tackle Pat Williams has been fined $5,000 for grabbing the facemask of San Diego quarterback Philip Rivers on a play in the first quarter. The play drew a 15-yard personal foul penalty.
Len Pasquarelli is a senior writer for ESPN.com