Fox lasted 15 plays in last week's win over Minnesota before leaving with a groin injury and not returning. He hasn't practiced all week.
Hilliard lost the starting right tackle job to Fox in the preseason in a competition that went right down to the end. That could be beneficial for the Lions in their current situation.
"When he's had to play he's gone in and done the job for us," Lions head coach Jim Schwartz said of Hilliard earlier this week. "We need 53 guys doing that.
"Whether they're inactive, a backup, a special teams player, a specialist or a starting player they all have a role when it comes to the week of preparation. Then (last Sunday) he did it."
Hilliard started four games in 2010 for Detroit and another in 2011, when he replaced Gosder Cherilus at right tackle for disciplinary reasons.
Expect free agent tackle
"Well, you never want to have a player miss a game and he's pretty good," defensive coordinator Gunther Cunningham said of Fairley. "He and (Ndamukong) Suh are playing pretty well together.
"I think C.J. Mosley played pretty well last week. I was excited. I wish he wouldn't wear (No.) 99, he kind of reminds me of (former Lions DT) Corey (Williams). And they're built the same way, he doesn't say much, he just plays and he had a good game last week. So we have depth there and hopefully Nick will be ready to play."
The Lions listed reserve safety