"Everything should be OK," Kubiak said. "I expect him here tomorrow. If that's the case, and he's doing what he normally does, he'll be out there."
Schaub's agent, Joby Branion, would not comment on Schaub's status.
Kubiak said he did not know how Schaub hurt his knee. He met with Schaub on Tuesday morning and said Schaub seemed fine. The quarterback left the Texans' training facility and called the team later in the day to say that his knee was bothering him.
He was hospitalized overnight, and Kubiak says the team wanted to keep him there Wednesday as a precaution.
"Just needed some rest, needed some treatment," Kubiak said. "We made a decision that it was best to get it there, then sit around here all day."
Schaub ranks fifth in the AFC in completion percentage (64.2) and yards passing (2,320). Dan Orlovsky is Schaub's backup, and Matt Leinart is next on the depth chart.
Schaub started every game last season and the first nine this year. He missed five games in 2007 with a shoulder injury and five more in 2008 with a strained ligament in his left knee.