The Lions were one of the NFL's worst rushing teams last season, averaging just 82.3 yards per game -- 30th in the league -- en route to the first-ever 0-16 campaign.
Metcalf, one of the newest players on a Lions team that has turned over more than half its roster since the last game of the winless season, said the opportunity was too good to pass up.
"I can compete for a job here," said Metcalf, who started about one-third of the games he played with the Bears. "It's a chance to work hard and show I belong here. That's all I've wanted."
"We've got ideas of our rotation; I think it will be pretty similar to the way we did it last week," he said. "We're really about two-deep, anyway, so we're trying to maintain that for the game."
Loper was a backup the last two seasons with the Tennessee Titans, and Manny Ramirez also has alternated with him on the first team in recent drills.
Jansen has seen a handful of snaps at center during camp and said he'll do whatever it takes -- including playing guard -- to be part of the regular unit on game days.
"I'd be most comfortable at tackle," the former University of Michigan standout said. "But if that doesn't happen, I want to be able to play wherever they need me. They're only going to have a few guys on Sundays. I want to be one of them."
Copyright 2009 by The Associated Press