The Houston Texans will likely have to rely on a thirdstring quarterback to try to clinch their first playoff berth in franchise history after backup Matt Leinart injured his throwing shoulder Sunday.

Leinart said he believed he broke his collarbone, but coach Gary Kubiak said initial X-rays were inconclusive. Starter Matt Schaub is already out for the season with a foot injury.

Leinart was hit hard by defensive end Jeremy Mincey late in the second quarter of Houston’s 20-13 win over Jacksonville.

The Texans (8-3) have a two-game lead over Tennessee in the AFC South with five games remaining.

Houston is down to T.J. Yates and newly signed Kellen Clemens. Yates completed 8 of 15 passes for 70 yards in relief of Leinart, doing just enough to help the Texans beat the Jaguars (3-8).

Houston has one of the league’s best running games. But as Jacksonville showed, Arian Foster and Ben Tate will have a tough time carrying the load against eightand nine-man fronts.

Redskins fullback Darrel Young and Seattle wide receiver Sidney Rice both left with concussions and did not return in Washington’s 23-17 win.

Broncos cornerback Cassius Vaughn injured an ankle in the first quarter of Denver’s 16-13 overtime win over San Diego and didn’t return.

Browns linebacker Scott Fujita likely broke his right hand in the fourth quarter of a 23-20 loss to Cincinnati but expects to keep playing.