According to sources, Foster suffered a torn Achilles tendon in his right foot with just under five minutes to go in the Texans' 44-26 loss to the Miami Dolphins. The injury happened without contact. Foster hopped off the field, putting minimal pressure on his right foot.
"I know he's hurting," O'Brien said Monday. "He worked hard to come back for the season, had the groin injury and now this injury. He's a guy that's proven he can come back from injury, and I'm sure once he's able to rehab it he'll rehab it very diligently and try to come back."
Foster had an MRI on Monday that showed a fully torn Achilles' tendon, according to a source.
"It's devastating," said left tackle Duane Brown, who is a close friend of Foster's. "Just because I know how much he puts into this thing, how much work he puts in to be great, to be healthy, and to stay on the field. I know how hard he worked to come back from his groin injury. To have this happen, I'm really hurting for him. I know it's pretty frustrating."
Foster played in four games this season, rushing for 163 yards on 63 carries with 227 yards receiving.
He missed the first three games of the season as he recovered from a torn groin he suffered on Aug. 3. That injury, which happened in the first fully padded practice of training camp, resulted in a surgery on Aug. 7 that reattached a muscle to the bone. Foster has missed games because of injury in four of the past five seasons.