METAIRIE, La. (AP) -- The New Orleans Saints will likely open the regular season with outside linebackers who are unfamiliar with coordinator Rob Ryan's new defense.
Following Will Smith's season-ending knee injury in Sunday's preseason game at Houston, the Saints acquired Parys Haralson through a trade with San Francisco.
He was due to have a physical Tuesday night, but coach Sean Payton says Haralson probably won't play in New Orleans' preseason finale in Miami on Thursday night.
Junior Galette, who has a minor leg injury, and Martez Wilson, who dislocated his elbow early in training camp, will compete with Haralson for two starting jobs.
But they have not played this preseason and are unlikely to play before the Saints start the regular season at home against NFC South rival Atlanta on Sept. 8.
The NFC champion 49ers had enough depth at linebacker to deal Haralson, a seven-year veteran who was in a reserve role while coming back from a torn left triceps that sidelined him last season.
"He's a player that there's a lot of film on. He has had a lot of experience as a starter there," Saints coach Sean Payton said after practice Tuesday evening.
"He's strong at the point of attack. He's experienced in this system and he's experienced and had success with a very good defense.
"His character and football IQ -- all those things are outstanding," Payton added.
Combined, Haralson, Galette and Wilson had one start in 2012. That went to Galette, who like Wilson was playing defensive end in the 4-3 scheme the Saints were running a year ago.
Ryan has switched the defensive front to a 3-4, the same front in which Haralson has played with the Niners.
A fifth-round draft pick by San Francisco in 2006, Haralson has played in 86 games with 68 starts. He's been credited with 295 tackles, 21 sacks, four fumble recoveries and three forced fumbles.
Last season, Galette played in 12 games and had five sacks.
Wilson played in all 16 games and had three sacks.
As outside linebackers in a 3-4 formation, both Galette and Wilson will have pass-rushing assignments similar to what they had as ends last season.
However, they will also have to cover short passing routes, though both appear to have the speed to handle that.
Galette made the team as an undrafted rookie in 2010.
Wilson was drafted in the third round as an outside linebacker in 2011, then moved to end in 2012.
He is back at linebacker, where he and Galette were expected to work as reserves behind Smith and Victor Butler, who was acquired as a free agent from Dallas.
Butler tore knee ligaments during an offseason practice in June, and has been designated as physically unable to perform, meaning he'll miss at least the first six games.
"It's going to be a challenge with depth," Wilson said.
"The team is expecting me to step up," Wilson added. "I'm always confident, always ready to compete, always feel like I can start. I just feel like I'm ready to come in and do my best every play, every practice."
Regardless of how the new starters perform, Saints players and coaches said Smith's experience and leadership would be missed.
Smith was the longest-tenured Saints player, drafted in the first round in 2004. Now the longtime defensive captain is on injured reserve for the first time in his career.
"I know he's frustrated because he put a lot of work in this offseason," Payton said, referring to Smith losing about 10 pounds and learning some new assignments in his transition from end to outside linebacker.
"He was handling all that well. It's frustrating and I'm disappointed for him."
Quarterback Drew Brees said losing a "mainstay" such as Smith was tough, but that Smith will still influence his defensive teammates when he returns from surgery for rehabilitation.
"I know his leadership is still going to be there," Brees said. "He's still very influential with the young guys that we have up front. He'll still be a part of this team."
