Peterson (ankle) and Ponder (hip) were both limited participants in Friday's practice. Ponder hadn't practiced all week until Friday, while Peterson did limited work the last two days.
"He was able to cut better, he still has a little bit of a gait when he runs, but he was better than yesterday," Frazier said of Peterson. "We will talk about it when we leave here, but he was better, incrementally better."
When asked why he was encouraged that Ponder might play, Frazier said, "He still has some soreness, but being able to see him drop back and deliver the ball and have accuracy and move around a little bit. That was encouraging, because yesterday he was pretty stiff.
So we will see how he feels tomorrow as well when he is throwing the ball around."
Backup quarterback Joe Webb has shared first-team reps with Ponder this week and would be in line to start if Ponder is unable to play.
The Vikings will try to snap a five-game losing streak in Detroit.
For a complete look at all injuries around the league, visit NFL.com's injuries page.