HOUSTON -- Ryan Fitzpatrick is set as the Houston Texans' starting quarterback. But a battle still remains for the team's backup role.

Coach Bill O'Brien said Wednesday he hasn't determined whether Case Keenum or rookie Tom Savage will play behind the veteran Fitzpatrick. Keenum is the expected backup. The former University of Houston standout started eight games last season and beat out T.J. Yates for a roster spot Tuesday.

"I've still got an opportunity to prove myself, to prove my ability as a quarterback, to take what I learn in the meeting room and transfer it to the field," Keenum said. "I have to show them I'm working hard to learn this offense and I'm capable of leading this team."

Savage, a fourth-round pick in the 2014 NFL draft, has been praised by the Texans. But O'Brien has regularly pointed out the rookie has much to learn. It's also difficult to envision the Texans immediately inserting Savage into an early regular-season game if Fitzpatrick goes down.

"He has a long way to go," O'Brien said.

For the first-year coach, it was a difficult decision to release Yates, whom O'Brien referred to as a "good pro."

"It's a weird deal," Keenum said. "(Yates) busted his tail since before I got here. We made each other a lot better. We competed since the day I got here and learned a lot. I've got the utmost respect for him, not just as a player, because he's also a great person. He helped me so much last year. There's not many people like that. T.J. is a good friend of mine."

O'Brien acknowledged the Texans could still add another veteran quarterback. But the team wants training camp repetitions split between three quarterbacks, which is part of the reason Yates was released before minicamp was complete.