Starting running back Jordan Howard, meanwhile, has yet to be cleared for contact as the result of a shoulder stinger, putting his status for Sunday's game against the New England Patriots in doubt. He is listed as questionable on the official injury report.
The 36-year-old Sproles, who moved past Hall of Fame receiver Tim Brown and into fifth place in career all-purpose yards this season, acknowledged on Instagram that it could be the end of the road after 15 seasons.
Ajayi has not played since last October, when he suffered a torn ACL while with the Eagles. Still, there appears to be a real chance that Ajayi suits up this weekend as an option behind rookie Miles Sanders and Boston Scott.
"Yeah, I think so," coach Doug Pederson said when asked if he'd be comfortable with Ajayi getting some snaps against New England. "Don't lose sight, too, De'Angelo Henderson is on our practice squad. He's another candidate that has been working really hard in our offense, knows our system, and has been here, too. So we have a couple of options there. If it's Jay, and really if it's either one, I think we can give them a little bit of work."
Ajayi was acquired by Philadelphia at the trade deadline in 2017 and helped the team during its Super Bowl charge, as he rushed for 408 yards and a touchdown in seven regular-season games and an additional 184 yards in the postseason.
Injuries limited him to four games in 2018.
Sproles suffered a partial tear of the hip flexor muscle Oct. 6 against the New York Jets, the team said in a statement. After a lengthy rehab, he returned Nov. 3 against the Bears. He reported the most recent injury after Wednesday's practice, the team said, and further testing revealed the torn hip flexor.
He had been listed on the injury report with a quadriceps problem.
Sproles appeared in six games this season, finishing with 66 yards on 17 carries.