McNown will not play Saturday night when the Dolphins face the Green Bay Packers at Lambeau Field, and Wannstedt said it was doubtful McNown would play in the preseason finale against Minnesota on Aug. 31.
That means if McNown is going to stick around, he is going to have to show the Dolphins coaches something during practice because Wannstedt said the Dolphins would not keep four quarterbacks on the 53-man roster.
The battle for the third quarterback job will come down to McNown or current No. 3 Mike Quinn because rookie Josh Heupel, who hasn't played or practiced since the Hall of Fame Game because of a wrist injury, is considered as good as gone.
Unless McNown totally flops, he's likely to beat out Quinn. Wannstedt talked with Quinn on the field after practice Wednesday and told him McNown had been brought in because the Dolphins feel they owe it to themselves to try to improve the team whenever they can.
While the arrival of McNown probably signified his demise with the Dolphins, Quinn said he would just go about his business.
"I'm not going to let this affect the way I practice or play," he said. "I plan on working just as hard as I always have."