ORCHARD PARK, N.Y. -- Coach Steve Mariucci's challenge to rebuild the Detroit Lions just got tougher.
Mariucci said Stewart will be examined immediately when the team returns home. But he didn't sound confident in pinpointing who would take Stewart's place should he not be ready for Detroit's regular-season opener against Arizona on Sept. 7.
"I don't know who the bellcow would be. I don't know who the lead dog would be," said Mariucci, in his first year with the Lions. "If we have a guy who's capable of 25 carries a game, I don't know that we have that person ready yet. It very well may be running back by committee."
That's not encouraging, considering the Lions had no proven backup heading into the season, and for a team coming off two losing seasons in which they went a combined 5-27 under former coach Marty Mornhinweg.
Mariucci didn't rule out the option of the team signing another running back.
Stewart, who led Detroit with 1,021 yards rushing last season, was hurt on the Lions' second series, which was also supposed to be his last of the game.
On a third-and-1, Stewart burst up the middle but was stood up at the line of scrimmage by Bills safety Coy Wire. Stewart was then tackled from behind by three other Buffalo defenders.
He left the field gingerly holding his right arm away from his body.
The Lions also lost linebacker Brian Williams, who dislocated his left shoulder.
Olandis Gary had the go-ahead score three minutes into the fourth quarter with a 1-yard run, followed by a two-point conversion by holder Brian Moorman, who ran it in off a bobbled snap.
Antonio Brown returned a punt 75 yards for a touchdown and Josh Reed had a 34-yard touchdown reception for the Bills (3-1).
Jason Hanson hit three field goals, including a 47-yarder, while Stephen Trejo recovered a fumble in the end zone for the Lions (2-2).
The Bills completed their first winning preseason since going 3-1 in 2000.
More important, Buffalo finished comparatively injury free.
Offensive guard Ruben Brown sustained a bruised left hand, but will be ready to open the season against New England on Sept. 7.
"It was good to see us finish up strong," coach Gregg Williams said. "We came out of it good, without any injuries of significance. I know (Detroit) had a few, which was unfortunate."
Without Stewart, the Lions are left to choose among Shawn Bryson, who's coming off knee surgery, Autry Denson, a four-year journeyman, and Avon Cobourne an undrafted free agent out of West Virginia.
Cobourne had the best outing, finishing with 19 yards rushing and set up the Lions' first score when he fumbled on the Bills' 1, and the ball was recovered by Trejo in the end zone. He also had two catches for 51 yards, including a 42-yarder off a screen pass, the Lions longest play from scrimmage this preseason.
"His injury was something that nobody ever wants," Cobourne said. "But it gives everybody else an opportunity now to play. We don't know what's going to happen. He might come back, hopefully he does."
Denson, who spent this year in NFL Europe, finished with 35 yards rushing on eight carries and six catches for 40 yards. He dropped an easy pass inside the Bills' 10 with 32 seconds left in the second quarter, forcing the Lions to settle for a Hanson field goal.
Bryson, recovering from a knee injury, saw limited action and finished with 10 yards on six carries.
Quarterback Joey Harrington, who was limited to two series, remained upbeat.
"I'm very confident that the guys behind him can come in and do a good job," Harrington said. "We've got guys that can come in and do it. It's just that they've never done it for us before. ... I'm excited to see what the new guys can do."
Buffalo, which opens the regular season against New England, took no chances, limiting most of its starters, including quarterback Drew Bledsoe, to one series.
- Combining regular season and preseason games, the Lions are 0-20 on the road since beating Indianapolis in the 2001 preseason.
- The Bills held out RB Travis Henry (foot) and OT Jonas Jennings (concussion).
- Buffalo improved to 9-13-1 in preseason games against Detroit.
The Associated Press News Service
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