NOTES: San Francisco DT Ray McDonald suffered a biceps injury and was ruled out midway through the third quarter. ... The 49ers defense already was without two All-Pros, ILB Patrick Willis and OLB Aldon Smith. Willis missed his second consecutive game due to a strained groin. Smith sat out a second game in a row while undergoing rehab in the wake of his arrest last month on suspicion of driving under the influence of alcohol. ... Texans starting RG Brandon Brooks (toe) was inactive. Backup C/G Ben Jones started in his place.