Behind the starters is a pair of former undrafted free agents, Jacques Cesaire and Brandon McKinney, and a former seventh-round draft pick, Ryon Bingham.
The Chargers elected not to pick up a defensive lineman in this year's draft, so the competition will come from last year's rookies. Defensive ends Andre Coleman and Keith Grennan spent all of last season on the practice squad, while nose tackle Keith Jackson joined the squad on Nov. 20.
Jacques Cesaire made the team as an undrafted free agent in 2003.
"I can't just strong-arm guys anymore because people are as strong as I am," Coleman said. "On this level, you have to rely on your technique. Little things like which hand you put down or the movement of an offensive lineman's shoulder can make all the difference."
Grennan (6 foot 4, 298 pounds) is a blue-collar player whose work ethic and grit make him popular with the coaches. He spent last season learning Ted Cottrell's scheme, as it was his first time in a 3-4 defense. After some exposure to the system, Grennan feels he's a stellar fit in the 3-4 alignment.
"I think I'm well suited for a defense like this," Grennan said. "I have the size and speed to play outside and bring pressure off the edge, and the size to play 3-technique inside against the run."
Speaking of size, Jackson has just enough of it to push McKinney for the right to back up Williams. The 6-foot, 315-pound lineman from Arkansas is a superb run-stuffer who's well suited to eat up space at the point of attack. He was a seventh-round pick of the St. Louis Rams in 2007, getting selected just eight spots after Brandon Siler.
Jackson knows what it takes to be successful in the NFL. His father of the same name spent nine years in the NFL playing tight end for the Philadelphia Eagles (1988-1991), Miami Dolphins (1992-1994) and Green Bay Packers (1995-1996). The elder Jackson earned six Pro Bowl invites and won a Super Bowl ring; his son has a shot to accomplish the latter feat as early as this season.
Michael Lombardo is a member of the Pro Football Writers of America and a long-time contributor to the Scout.com network. His analysis has been published by the NFL Network, Fox Sports and MySpace Sports. He has followed the Chargers for more than 15 years and covered the team since 2003.