Schaub practiced on Thursday, and coach Gary Kubiak expects his No. 1 quarterback to start when the Texans (4-5) visit the New York Jets (7-2) on Sunday.
Kubiak said Schaub took about half the first-team snaps on Thursday. The only way Schaub will not start is if he has a setback before the game.
"Everything we thought would happen today happened," Kubiak said. "Everything is pointing in the right direction."
Schaub acknowledged that his knee has been bothering him most of the season. He said the pain increased on Tuesday morning and checked into a hospital later in the day. He stayed overnight and studied the playbook and a video of Wednesday's practice during his stay. He said the knee didn't bother him during Thursday's workout.
"It feels good and it's ready to go," Schaub said. "There is no doubt in my mind I'll be playing on Sunday."
Schaub said the injury will not require surgery. He's started the last 25 games for Houston after missing five games in 2008 with a strained ligament in his left knee. He also missed five games in 2007 with a shoulder injury.
Schaub had no explanation for why the injury flared up, but he said it won't limit his movement in Sunday's game. He says he feels no pain in his knee when he runs or throws.
"It was just kind of weird Tuesday morning when I woke up, the way it was and everything," he said. "It was out of ordinary."
Orlovsky started seven games for Detroit in 2008, when the Lions became the first team in NFL history to go 0-16. He hasn't taken a snap in a regular-season game since signing with the Texans in March 2009.
"Like I said, I'll prepare the same way," Orlovsky said. "I honestly felt that I did a good job of preparing with our offense every single week and I won't change that. My job is to get ready to play no matter what the case is. I'll be ready."