Houston Texans coach Gary Kubiak has revealed that he is optimistic about running back Arian Foster's chances of playing in the opening game of the season.

Foster has suffered a string of niggling injuries during the pre-season campaign which have kept him on the physically unable to perform list.

The 26-year-old was originally placed on the PUP list due to a calf injury, but soon began complaining of soreness in his back and, more recently, his legs. However, Kubiak is hoping that he will be fit for that start of the regular season.

"I am [optimistic], because I watch him work. I've been watching him — he's basically going through practice or has been since we've been in camp on his own with [head trainer] Geoff [Kaplan]," Kubiak told reporters.

"And, obviously, there's been a little setback as we try to get the soreness out of him. But from what I've seen, yes, because it's not like he's been standing around for the last three weeks."

The Texans will kick off their new season at the San Diego Chargers on September 9.