It is the first fine levied against a San Francisco player this season and believed to be the first time that Adams, a fourth-year veteran, has drawn any kind of league sanction. The fine is the latest by the NFL in the league's increasing efforts to protect quarterbacks.
In the first six weeks of the season, there have been more than a dozen fines against defensive players for what the NFL has deemed as excessive contact against quarterbacks.
There was an earlier personal foul called in the game for a hit on Rivers, but that play did not merit review by the NFL, and thus, did not draw a fine.
The incident for which Adams was fined occurred on the first play of the fourth quarter. With the Chargers facing a third-and-9 at their own 37-yard line, Rivers dumped a short pass to tailback LaDainian Tomlinson for a 16-yard gain.
Adams hit Rivers after he released the ball, driving him to the ground, and was flagged for a 15-yard personal foul, moving the ball to the San Francisco 32-yard line. The possession concluded with a Nate Kaeding 44-yard field goal.
A fourth-year veteran, Adams said earlier this week that the contact on Rivers was unintentional, and suggested he should not be fined. It is not yet known if Adams will appeal the league action. The $5,000 fine is fairly standard for a first-time offense. New York Giants middle linebacker Antonio Pierce was fined $12,500 this week for hitting Atlanta quarterback Michael Vick while he was out of bounds in last Sunday's game.
Len Pasquarelli is a senior NFL writer for ESPN.com.