Foster made headlines last week when he linked a picture of an MRI of his injured left hamstring to his Twitter account.
"His workouts continue to get better, but he did not practice," said Houston head coach Gary Kubiak. "Everything's still progressing the same way, but obviously we're getting close to game time. We'll see where he's at tomorrow, but he was unable to practice today."
Foster, who had arthroscopic surgery on his right knee in the offseason, burst onto the scene in 2010 -- his second year in the league -- and totaled 2,220 yards from scrimmage, including a league-leading 1,616 rushing yards, to go with 18 touchdowns.
He re-signed with Houston in July before aggravating his hamstring during the preseason.