Willis sustained a toe injury and underwent examination in the locker room during halftime.
Willis, selected for the Pro Bowl seven times in his eight-year career, entered the game with 26 tackles and one interception in five games.
Patrick Willis is on the sideline in street clothes, his left foot in a walking boot.— Matt Barrows (@mattbarrows) October 14, 2014
Backup safety Jimmie Ward and starting guard Mike Iupati were also taken out of the game during the second half. So far, the team has only said Ward would not return.