Bears linebacker Lance Briggs limped off the field last night and didn't return in, casting doubt on the Pro Bowl linebacker's availability for the season opener Sept. 12 against the Detroit Lions according to Neil Hayes of the Chicago Sun-Times. Briggs injured his left ankle early in the first quarter of the 14-9 loss to the Arizona Cardinals on Saturday night at Soldier Field. Briggs was unavailable after the game. Although the severity of the injury wasn't known, he was seen leaving the stadium wearing a walking boot. That isn't good news for a defense that has struggled during the preseason. ''We don't know the extent of the injury or anything right now, but he couldn't finish the game,'' coach Lovie Smith said. Source: Chicago Sun-Times