Case Keenum presents the Texans with a much more mobile quarterback than the recently benched Matt Schaub.

But Indianapolis’ defense is led by 11-year veteran Robert Mathis, and his league-leading 11.5 sacks have already drawn the attention of the Texans’ offense.

“Very much (worried),” coach Gary Kubiak said Thursday at Reliant Stadium. “He’s playing everywhere. If he gets you in must-pass situations, not many people have blocked him this year. And for a guy that’s not a big player, he can play power football, too, when you watch some of the plays he made against Denver in that game.

“We’re well aware. It’s easy to say you’ve got to go in to help this guy or chip this guy or do that, but they’re going to play Mathis enough places where it’s going to be difficult. Us running our offense and not having third-and-12, third-and-10, those types of things will help more than anything.”