The Texans finally have pinpointed what is wrong with Jerome Mathis' left leg, and it's enough to likely sideline him for the rest of the season. After almost two days of testing, team doctors found a "hot spot" in the lower part of his leg, which is causing excruciating pain for Mathis during and after running. The Texans are expected to place Mathis, 24, on injured reserve and sign wide receiver Harry Williams off the practice squad for the game against Miami on Sunday at Reliant Stadium. "He has a stress-related issue in his lower leg," coach Gary Kubiak said Friday. "Our issue right now is trying to make a decision of how long it's going to be before he can get back on the field."