Williams, the Texans' all-time sacks leader, is out for the season after tearing a pectoral muscle in Sunday's 25-20 loss to Oakland. Second-round draft pick Brooks Reed will step in at outside linebacker. Johnson is also likely to miss Sunday's game at Baltimore (3-1) with a right hamstring injury.
The Texans acquired veteran Derrick Mason from the New York Jets to boost the receiving corps without Johnson, who was injured in Houston's 17-10 win over Pittsburgh in Week 4.
