Asked if he could count on Foster to play in the season opener, Kubiak said he could.
"I am, because I watch him work ... with (trainer) Geoff (Kaplan)," Kubiak said Monday. "Obviously there's been a little setback as we try to get the soreness out of him. It's not like he's been standing around for the last three weeks."
Foster remains on the physically unable to perform list while recovering from back soreness. He initially was placed on the PUP list with a calf injury he suffered during organized team activities.
But once his calf healed, back soreness began to bother Foster, who received injections to help with the soreness before the Texans' first preseason game. Kubiak said Sunday that the injections caused pain in Foster's legs.
Without Foster, Ben Tate is the Texans' only running back on the roster with significant experience in an NFL offense. Three undrafted rookies and young veteran Deji Karim are competing for the third roster spot.