Foster, the NFL's leading rusher in 2010, has a sore knee and Reed has a sore hip. Foster, who sat out last year's opener with a left hamstring injury, says his knee just needed rest. He wouldn't specify which knee was hurt.
"I expect to play on Sunday," Foster said.
Reed, a second-round pick in last year's draft, did not speak to the media on Friday. Kubiak is "optimistic" that both players will be ready, but he'll work out both of them before Sunday's game.
"If we pushed him (Foster) to practice, he would've went out there and practiced," Kubiak said. "But we're going to be smart with him, but then he'll have to show us he's ready to go. I think Brooks is a little bit more sore than Arian, as far as going out on the field, but he is also optimistic that he'll be ready to go. But we'll have to test them both."
Kubiak says Foster "practiced fine" on Thursday. He says Reed came out of an individual drill and felt a "twinge" in his hip.
Ben Tate would start for Foster and first-round draft pick Whitney Mercilus would start for Reed, if either regular starter can't go on Sunday. Tate made two starts and had four 100-yard rushing games in 2011. Mercilus led the Football Bowl Subdivision in sacks per game last season at Illinois (1.23).
"If Brooks can't go, Whitney's got to play more," defensive co-ordinator Wade Phillips said. "We expected Whitney to play, but he's got to be ready to go."