The defending champion Saints will have to try to repeat without their top two power running backs.

Pierre Thomas, one of the stars of last season's Super Bowl run, was placed on injured reserve on Wednesday because of his injured ankle. The Saints made that move only one day after placing leading rusher Chris Ivory on injured reserve because of a left foot injury that occurred during Sunday's regular season finale.

"That's tough," quarterback Drew Brees said of the loss of both running backs this week. "You can't deny that just because of the physical presence they bring and obviously their productivity."

When the Saints (11-5) open the playoffs in Seattle (7-9) on Saturday, the only remaining healthy running backs from their regular season roster will be Reggie Bush and Julius Jones.

"Naturally, I'm going to have to step up," Bush said.

Bush missed eight games with a fracture in his lower right leg. He has rushed for only 150 yards and has not scored a rushing touchdown this season, but started to look stronger on Sunday against Tampa Bay, when he had 70 yards rushing on just nine carries and had 55 yards receiving on five catches.

Jones has 193 yards and no touchdowns rushing. The only other running backs on the roster are fourth-year pro DeShawn Wynn, who was signed on Tuesday but also was with the Saints during the preseason, and rookie Joique Bell, who was signed Wednesday from the Philadelphia Eagles' practice squad.

Brees said he remained optimistic that the versatility of the Saints' offense and the way they spread the ball among so many players will allow them to weather such injuries perhaps better than most teams.

"In the end, you just work to the strengths of the guys that you have. You don't worry about what you don't have, just what you have," Brees said. "While you would love to have all of the guys and all of the elements that they bring, I feel like Reggie Bush can do some pretty special stuff and Julius Jones can do some pretty special stuff. Deshawn Wynn, when called upon, can do the job. You realize that the passing game may have to pick up some slack at times depending on how the game plan changes by having those guys in."

Bush, who returned from his broken right fibula on Thanksgiving, said he has been feeling stronger lately and is looking forward to the chance to be the primary running back. However, he stressed that the success of the offense would hinge on many more factors than him.

"It's about a team effort. It's not just about one person," Bush said. "We have some mistakes that we made as a team throughout the season on offense, defense and special teams that we've got to clean up. The running back position is just one small piece of the puzzle."

Yet as the playoffs approached, the Saints had been optimistic their offense would be better with Thomas, who scored memorable touchdowns in both the NFC title game and Super Bowl last season.

Dealing with a left ankle injury that limited him to only six games this season, Thomas started to look effective again in a 17-14 victory at Atlanta in Week 16, when he had 102 yards from scrimmage and a touchdown.

However, he aggravated the injury in practice last week and sat out the regular season finale.

"The setback he had was substantial and we're at that point in the season where you want to do what's best, and yet you want to be mindful of the injury the player has," Saints coach Sean Payton said. "So I think on all fronts — doctors, trainers, the player and ourselves — we felt that this was the best move."

Thomas initially was hurt in an overtime loss to Atlanta in Week 3, then missed nine games before coming back for three late-season games. He finished with 269 yards and two touchdown rushing and caught 29 passes for 201 yards.

Late this season, Thomas also had handled kickoff returns after Courtney Roby was placed on injured reserve with a head injury.

Payton said receivers Devery Henderson and Robert Meachem are getting most of the practice time in that area this week.

Ivory's injury is a Lisfranc, which is a fracture and dislocation in the mid-foot, and will require surgery, Payton said. After joining the Saints as an undrafted rookie out of Division II Tiffin, he rushed for 716 yards in 12 games and had a team-leading five rushing TDs.

Payton said he was not prepared to discuss whether Thomas will need surgery. Thomas, who entered the NFL with the Saints as an undrafted rookie in 2007, was playing under a one-year contract as a restricted free agent this season.

Notes: Saints WR Marques Colston practiced fully on Wednesday after missing practice and the game last week while recovering from what Payton described as minor arthroscopic surgery on his right knee. ... Tight ends Jeremy Shockey (groin) and David Thomas (right knee), who both missed last Sunday's game, practiced on a limited basis, while fellow tight end Jimmy Graham (sprained left ankle) sat out. ... Also missing practice were safety Malcolm Jenkins (right knee), defensive lineman Anthony Hargrove (left knee), and linebacker Danny Clark (hamstring).