Coach Jim Schwartz didn't say Wednesday when Stafford might play again.
"We're going to start Shaun Hill at quarterback on Sunday, and then after that we'll see what happens," Schwartz said.
Stafford was back at practice but stood to the side in his jersey and a baseball cap while Hill and Drew Stanton participated in drills during the portion of practice open to reporters.
Stafford was knocked out of the season opener when Chicago's Julius Peppers sacked him Sunday, putting him on the sideline with a banged-up right shoulder -- his third injury in two seasons. Stafford's father, John Stafford, said his son was going to visit well-known sports Dr. James Andrews this week.
"He's really frustrated, but still upbeat," John Stafford told The Associated Press. "I know he's going to get over this hurdle."
Stafford missed six games last year after being the No. 1 pick in the draft because of a banged-up left shoulder and right knee. Hill took Stafford's place during last weekend's 19-14 loss to the Bears.
"Everybody plays this game to actually play it, not just to practice," Hill said. "So I'm very excited for the opportunity."
Schwartz said earlier in the week he didn't think Stafford would need surgery. He said Wednesday not much had changed in the last couple days, but wouldn't go into more detail.
"I'm not going to comment on what our doctors tell a player," Schwartz said. "I'm not going to comment on what results of an MRI are, or any of those things. That's just the way it is."
Last season, the Lions lost all six games when Stafford was out with injuries, struggling with Daunte Culpepper and Stanton leading the offense. Hill, meanwhile, was making six starts for the 49ers, winning three.
Detroit traded a seventh-round pick to San Francisco in March to acquire the 30-year-old Hill.
"Obviously, the more experience you have in this league, the better off you're going to be, so that helps," Hill said.
Hill went 9 for 19 for 88 yards with an interception last weekend. He had a pass to Calvin Johnson in the end zone ruled incomplete in one of the day's most controversial decisions -- the Lions thought they'd scored a go-ahead touchdown.
"He doesn't have a long period of being inactive," Schwartz said. "He's a veteran quarterback -- he's been around a long time, he knows how to prepare, he knows how to be ready for those situations, he's been in that role before."
The game against the Eagles could be a battle of backups. Philadelphia quarterback Kevin Kolb is going through concussion testing after getting hurt in a loss to Green Bay last weekend.