Grant, the team's co-leader with three sacks, was placed on injured reserve because of a triceps injury that he suffered in the Saints' last game on Oct. 26 against the San Diego Chargers in London.

Grant was hurt during the game, but he managed to return and finish the contest -- the last before the Saints' bye. It was not known if Grant was able to practice last Wednesday or Thursday, or when they returned on Monday, because each of those workouts was closed to media.

When the Saints play the Atlanta Falcons on Sunday in the Georgia Dome, Grant will become the 27th player on the 53-man opening day roster to miss at least one game this season because of injury. He will be the 13th starter on offense or defense to be sidelined and the third to wind up on injured reserve -- joining cornerback Tracy Porter and kicker Martin Gramatica.

The loss of Grant is a big one because the Saints are thin at the position. Bobby McCray likely will take over Grant's starting job and team with right end Will Smith, but the only other end on the roster is Jeff Charleston. It's likely the team will sign another end before practice on Wednesday.

Grant, a former first-round draft pick who's missed only two games since entering the league in 2002, has been a starter at left defensive since 2003. In 102 games and 90 starts, the 6-foot-3, 285-pounder has 41 1/2 sacks, which is 10th all-time in Saints history, and has 452 tackles, 13 forced fumbles, five fumble recoveries and an interception.

"Charles has played a key role for our team since we drafted him six years ago," Saints general manager Mickey Loomis said in a statement. "This is obviously a loss for our defense, but injuries are a part of our league and it presents an opportunity for other players to step up and answer the call."

Grant has had a bad year off the field. He was indicted for involuntary manslaughter for his alleged part in a February brawl outside of a Blakely, Ga., nightclub that led to the shooting death of a pregnant woman. That case is still pending.

Grant also reportedly was one of four Saints who tested positive for a banned diuretic this summer. He and Smith, along with running back Deuce McAllister, reportedly face a four-game NFL suspension for using an over-the-counter diuretic called Bumatanide that can mask the use of steroids.