Facing the possibility of starting their third quarterback in the past five games, the Houston Texans signed Case Keenum on Monday while awaiting word on rookie Tom Savage’s knee injury.

Savage was forced into action Sunday at Indianapolis and was overwhelmed — physically and mentally — in the 17-10 loss that eliminated the Texans from playoff contention.

He entered the game when starter Ryan Fitzpatrick was carted off with a fractured tibia that will require surgery.

Fitzpatrick returned to the starting lineup when quarterback Ryan Mallett, who was named the team’s starter during the Nov. 9 bye week, lasted two games and 75 pass attempts before he was placed on injured reserve with a torn pectoral muscle.

Keenum started eight games for the Texans last season. The 26-year-old starred at University of Houston and became the starter in 2013 when Matt Schaub struggled to a 2-6 start for a team that had playoff goals. The Texans finished 2-14.

Coach Bill O’Brien is unlikely to determine the pecking order at the position until Wednesday. If Savage is healthy, he could still be back on the bench given his play Sunday.

Thad Lewis, who started multiple games for the Buffalo Bills last season, remains on the roster and could start ahead of Keenum.