Grant definitely won't play in this week's home opener against Buffalo, McCarthy said, and the prospects could be much worse.
"It's a significant injury to the ankle and the ligament involved in the ankle, which has now required more testing, and we'll continue to process all the information throughout the day," McCarthy said. Team doctors didn't know whether surgery would be required, McCarthy said.
Grant, who is coming off of back-to-back 1,200-yard seasons, was injured at the end of consecutive runs of 13, 8 and 18 yards in the second quarter. In Grant's absence, Brandon Jackson and John Kuhn picked up the slack. Jackson carried 18 times for 63 yards and added two receptions for 12 yards. He delivered an 18-yard run and a 13-yard reception, both of which set up touchdowns. Kuhn, whose main role is as a fullback, carried two twice, with his leg-churning 12-yard run setting up his 3-yard touchdown.
Jackson has developed into a bulldog in pass protection on passing downs but has seen his opportunities with the ball dwindle since his rookie season, but he'll be the main man this coming week at the least.
Is he up to the task?
"I feel Brandon Jackson carried the load yesterday," McCarthy said. "I think there's a lot of evidence right there, recent evidence that he's able to play all three downs, and he will have that opportunity this week vs. Buffalo."
The other significant injury was to defensive end Justin Harrell. Harrell, playing his first regular-season game since December 2008, sustained a torn ACL and will be placed on season-ending injured reserve.
"Justin's has had a tough go from a medical standpoint," McCarthy said. "I've seen players in this league sometimes have injuries in bunches and then they're able to overcome them and go on to have a good career, and I was hoping Justin would fall into that category, and now he has another hurdle that he has to get over."
When Harrell is put on IR, that will open up a roster spot, either for another halfback or for a defensive lineman. McCarthy said a decision on whether to add a halfback will be made after the extent of Grant's injury has been determined. As for a defensive lineman to replace Harrell, the depth behind the starters are rookies Mike Neal and C.J. Wilson. Wilson was kept in favor of Jarius Wynn, a sixth-round pick last year who was released in this year's final cuts and remains unsigned. His signing seemed like a foregone conclusion.
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