The quarterback will be No 2 against the Cowboys, then drop to No 3 behind Grossman and John Beck for the final two games of the season.
McNabb's future in jeopardy at Redskins
Donovan McNabb has been relegated to second-string quarterback. Soon he will be the third-string. And there is no guarantee that he will be playing for Washington next season.
The ever-dramatic Redskins created a controversy again this week when Mike Shanahan, their coach, announced that Rex Grossman will be his starter for the rest of the season, beginning with today's game at Dallas.
McNabb will be the No 2 quarterback against the Cowboys, then drop to No 3 behind Grossman and John Beck for the final two games of the season.
And after that?
"I also told him," Shanahan said, "that I cannot guarantee him that he will be back next year."
That is how far the 34-year-old, six-time Pro Bowl quarterback has fallen. The player acquired with such fanfare in an April trade has been benched for his woefully inconsistent performances. He has thrown a career-high 15 interceptions and ranks 25th in the NFL in quarterback rating.
Asked if getting McNabb was a mistake, Shanahan said: "I think there's a lot of mistakes that you make. You really don't know if you made a mistake, but if you do make one, you make it and you go on. What I want to do is evaluate where we're at … then I will tell you if we erred or not."
McNabb's performance has the coach leaving all options open at the team's most important position for 2011. Shanahan said he had been planning to make the move after the Redskins were mathematically eliminated from the play-offs, which happened last weekend after a 17-16 loss to Tampa Bay.
"I've got to find where Rex Grossman is, where John Beck is. I want a chance to evaluate these guys," Shanahan said.
"I told Donovan that there's nothing he could do in the three games that would influence me over what he's done over the last 13 games.
"I said, 'I'm not sure what I'm going to do in the college draft, if we're able to get the top quarterback in the draft, if there was a young Donovan McNabb or maybe a Sam Bradford, someone like that.' There's a lot of possibilities."
McNabb did not comment, saying "No! No! No!" to reporters as he entered Redskins Park after training on Friday.
Grossman did speak, however, and he is aware that fans and pundits nationwide are ridiculing his promotion.
"I think everybody has doubters," said Grossman, who led Chicago to a Super Bowl during the 2006 season but has thrown 33 touchdown passes and 36 interceptions in 31 career starts.
"And any situation, until you prove yourself on a consistent basis, you're always going to have doubters, no matter what profession you're in.
"It's motivation. I'm human. How could you not be motivated to show everybody who's mocking this, or talking on the radio or TV thinking they're smart?"
McNabb was benched only once in 11 years with Philadelphia, and he has already doubled that total with the Redskins in less than one season.
Shanahan replaced McNabb with Grossman in the final two minutes against Detroit in October with the game on the line, a stunning decision made even more bizarre by Shanahan's mangled explanations.
The coach first said he felt Grossman had a better grasp of the team's two-minute offence, then said McNabb lacked the "cardiovascular endurance" to run a fast-paced drill because of nagging hamstring injuries.
Before the next game, the Redskins gave a McNabb a five-year contract extension nominally worth US$78 million (Dh286m) - but the only thing it guaranteed was that the quarterback would receive an extra $3.5m this season. The deal contains a clause that allows the Redskins to cut McNabb before next season with no further financial obligation.
This week, the situation began to take more strange turns.
Shanahan on Wednesday refused to say who would start today, saying he did not want to tip off the Cowboys. McNabb said he would expect to know by Wednesday if he was not starting, calling it a matter of "professionalism".
On Thursday, Kyle Shanahan - the coach's son and offensive co-ordinator - seemed to go out of his way to avoid praising McNabb while meeting with reporters. But he implied McNabb was still the starter.
Grossman said on Friday he had "hints" that something like this was coming, mostly from the way he was being used in practice. Mike Shanahan said he informed McNabb and Grossman of the move on Thursday afternoon.
"I knew this was going to be a circus once I talked about this," the coach said. "I wanted two good days [of practice], not having a lot of distractions."
The players were told on Friday morning.
"As sad as it is, this league is a what-have-you-done-for-me-lately league," DeAngelo Hall, the cornerback, said. "He hasn't won a whole lot of games with us. Coach felt like it was time to figure out if Rex is going to be the guy we keep around here next year."