Simpson set the tone for the day when he injured his foot in pregame warm-ups running a pass pattern.
The Redskins came into the game with three starters sidelined due to injuries, and running back Clinton Portis lasted only five carries before re-injuring his groin.
At least seven Redskins were hurt, though some returned:
Portis acknowledged the possibility that he could miss the remainder of the season. "Is it possible? Anything is possible, bro, but who knows?" Portis told The Washington Post.
Shanahan also said running back Ryan Torain is likely to miss Sunday's game against the Minnesota Vikings.
"It's tough, because you see your team out there in a tight game and you want to be out there, you want to help your teammates, you want to be a part of it," Rabach told The Post. "It's real tough to sit there and watch from the sidelines."
"If I had to go with my gut, I would think that it's not as serious as ones I've had in the past," Alexander told the newspaper. "I couldn't even stand on the sideline and walk around, it was so painful," Alexander said, describing a hamstring injury from a few years ago. "This one wasn't nearly as painful. ... I wanted to be smart. I didn't want to turn a week-or-two injury into the whole season."
» Veteran guard Derrick Dockery, who entered the game following Rabach's injury, suffered a knee injury. Dockery, who told The Post he suspects he injured his medial collateral ligament, will join the MRI crowd on Monday. "I was excited to get back out there," Dockery said. "I wanted to get the win. It's kind of disappointing, because I got hurt. Just got to find out the severity of the injury and move on."
The Post reports that the team will promote running back James Davis from the practice squad Monday, according to two league sources.
Shanahan said the team will sign a safety with the open roster spot.
The Associated Press contributed to this report.