According to the article, his likely replacement is Navies...
Niners' Lawson tears ACL in practice, lost for season
ESPN.com
Updated: September 20, 2007, 2:55 PM ET
The San Francisco 49ers suffered their first major injury blow of the season Thursday when they learned linebacker Manny Lawson was lost for the season because of a torn ACL.
Lawson suffered the knee injury late in practice Wednesday and a subsequent MRI revaled the tear. He will require season-ending surgery and will eventually be placed on the injured reserve list.
"I heard a pop, and I remember what (teammate) C.J. Brewer had talked about when he (injured his knee), so I was nervous," Lawson told the team's Web site. "I tried to test it out, but really I just had to wait for the MRI."
Lawson was a first-round draft pick in 2006 who signed a five-year deal worth a maximum value of $10.14 million. In 16 games as a rookie, including 11 starts, Lawson had 57 tackles, 2½ sacks, one interception and two passes defensed.
This season, he was coming into his own this season as a pass-rusher.
His likely replacement is veteran Hannibal Navies in the 49ers' 3-4 defense.