Packers coach Mike McCarthy said Wednesday that Starks "is our No. 1 back right now going into Detroit."
"He's played very well; he's earned that opportunity," McCarthy said. "I'm not a big believer in just riding one running back the whole season. We'll stay with the one-two punch."
The shift still constitutes a major change for the Packers, who have used Lacy as their workhorse back in his first two seasons. The two-time 1,100-yard rusher has just 308 yards at the halfway point of this season.
"It's still a tandem, a one-two punch," Starks said. "And that's how it's going to continue to be."
Starks, a sixth-year pro, is the Packers' leading rusher with 334 yards in eight games on five fewer carries than Lacy has this season. Starks actually started the Oct. 18 game against the San Diego Chargers and rushed for a season-high 112 yards on just 10 carries. In the same game, Lacy carried just four times for three yards.
"As a team, we're pretty much doing what's needed, going with what's necessary at this time," Lacy said. "This season he's definitely been the better player between the both of us. That's just the move."
Lacy, the 2013 NFL offensive rookie of the year, left Sunday's loss to the Carolina Panthers because of a groin injury after he carried just five times for 10 yards and lost a fumble. Lacy was also slowed by a sprained right ankle early in the season.
However, the injuries don't appear to be the impetus for this move, considering that McCarthy said he expected Lacy to be "full go" at practice Wednesday.
Lacy's weight, listed at 234 pounds, has been a topic of conversation throughout the season. However, Lacy insisted recently that he had not been fined for being overweight.